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HfTe3 single crystal undergoes a charge-density-wave (CDW) transition at TCDW = 93 K without the appearance of superconductivity (SC) down to 50 mK at ambient pressure. Here, we determined its CDW vector q = 0.91(1) a* + 0.27(1) c* via low-temperature transmission electron microscope and then performed comprehensive high-pressure transport measurements along three major crystallographic axes. Our results indicate that the superconducting pairing starts to occur within the quasi-one-dimensional (Q1D) -Te2-Te3- chain at 4–5 K but the phase coherence between the superconducting chains cannot be realized along either the b- or c-axis down to at least 1.4 K, giving rise to an extremely anisotropic SC rarely seen in real materials. We have discussed the prominent Q1D SC in pressurized HfTe3 in terms of the anisotropic Fermi surfaces arising from the unidirectional Te-5px electronic states and the local pairs formed along the -Te2-Te3- chains based on the first-principles electronic structure calculations.

The authors construct a M-shaped double superconducting dome and reveal the correlation between the CDW order and superconductivity in the Kagome metal RbV${}_{3}$Sb${}_{5}$.

We investigated the effect of pressure on the crystal structure and transport properties of the Magn\'eli phase \ensuremath{\eta}-${\mathrm{Mo}}_{4}{\mathrm{O}}_{11}$, which at ambient pressure undergoes two successive charge-density-wave (CDW) transitions at ${T}_{\mathrm{CDW}\text{\ensuremath{-}}1}\ensuremath{\approx}105\phantom{\rule{0.28em}{0ex}}\mathrm{K}$ and ${T}_{\mathrm{CDW}\text{\ensuremath{-}}2}\ensuremath{\approx}30\phantom{\rule{0.28em}{0ex}}\mathrm{K}$, respectively. We find that \ensuremath{\eta}-${\mathrm{Mo}}_{4}{\mathrm{O}}_{11}$ exhibits a structural phase transition from the low-pressure monoclinic $P{2}_{1}/a$ phase to a high-pressure $P{2}_{1}$ phase at ${P}_{c}\ensuremath{\approx}3.5\phantom{\rule{0.28em}{0ex}}\mathrm{GPa}$. Around ${P}_{\mathrm{c}}$, the lattice parameters experience a sudden change with a large volume collapse of $\mathrm{\ensuremath{\Delta}}V/V=\ensuremath{-}8.1%$, while the room-temperature resistivity exhibits a sudden jump by two orders of magnitude, signaling a pressure-induced metal-to-insulator transition. For $Pl{P}_{c}$, the high-pressure resistivity measurements revealed opposite pressure dependences of these two CDW transitions, i.e., ${T}_{\mathrm{CDW}\text{\ensuremath{-}}1}$ is enhanced gradually to \ensuremath{\sim}130 K while ${T}_{\mathrm{CDW}\text{\ensuremath{-}}2}$ is almost suppressed completely by the application of 2.6 GPa pressure. For $P\ensuremath{\ge}{P}_{c}$, the temperature dependence of resistivity changes to an insulating-like behavior, but the activation energy is reduced gradually upon further increasing pressure. We have rationalized the insulating ground state of the high-pressure phase in terms of the structural modifications and charge redistribution based on the refinement of single-crystal x-ray diffraction data at 8.9 GPa.

${\mathrm{CsV}}_{3}{\mathrm{Sb}}_{5}$ is a newly discovered ${Z}_{2}$ topological kagome metal showing the coexistence of a charge-density-wave (CDW)-like order at ${T}^{*}=94\text{ }\text{ }\mathrm{K}$ and superconductivity (SC) at ${T}_{c}=2.5\text{ }\text{ }\mathrm{K}$ at ambient pressure. Here, we study the interplay between CDW and SC in ${\mathrm{CsV}}_{3}{\mathrm{Sb}}_{5}$ via measurements of resistivity, dc and ac magnetic susceptibility under various pressures up to 6.6 GPa. We find that the CDW transition decreases with pressure and experience a subtle modification at ${P}_{c1}\ensuremath{\approx}0.6--0.9\text{ }\text{ }\mathrm{GPa}$ before it vanishes completely at ${P}_{c2}\ensuremath{\approx}2\text{ }\text{ }\mathrm{GPa}$. Correspondingly, ${T}_{c}(P)$ displays an unusual $M$-shaped double dome with two maxima around ${P}_{c1}$ and ${P}_{c2}$, respectively, leading to a tripled enhancement of ${T}_{c}$ to about 8 K at 2 GPa. The obtained temperature-pressure phase diagram resembles those of unconventional superconductors, illustrating an intimated competition between CDW-like order and SC. The competition is found to be particularly strong for the intermediate pressure range ${P}_{c1}\ensuremath{\le}P\ensuremath{\le}{P}_{c2}$ as evidenced by the broad superconducting transition and reduced superconducting volume fraction. The modification of CDW order around ${P}_{c1}$ has been discussed based on the band structure calculations. This work not only demonstrates the potential to raise ${T}_{c}$ of the V-based kagome superconductors, but also offers more insights into the rich physics related to the electron correlations in this novel family of topological kagome metals.

Impurity pinning has long been discussed to have a profound effect on the dynamics of an incommensurate charge density wave (CDW), which would otherwise slide through the lattice without resistance. Here we visualize the impurity pinning evolution of the CDW in ZrTe3 using the variable temperature scanning tunneling microscopy (STM). At low temperatures, we observe a quasi-1D incommensurate CDW modulation moderately correlated to the impurity positions, indicating a weak impurity pinning. As we raise the sample temperature, the CDW modulation gets progressively weakened and distorted, while the correlation with the impurities becomes stronger. Above the CDW transition temperature, short-range modulations persist with the phase almost all pinned by impurities. The evolution from weak to strong impurity pinning through the CDW transition can be understood as a result of losing phase rigidity.

CsV_{3}Sb_{5} is a newly discovered Z_{2} topological kagome metal showing the coexistence of a charge-density-wave (CDW)-like order at T^{*}=94 K and superconductivity (SC) at T_{c}=2.5 K at ambient pressure. Here, we study the interplay between CDW and SC in CsV_{3}Sb_{5} via measurements of resistivity, dc and ac magnetic susceptibility under various pressures up to 6.6 GPa. We find that the CDW transition decreases with pressure and experience a subtle modification at P_{c1}≈0.6-0.9 GPa before it vanishes completely at P_{c2}≈2 GPa. Correspondingly, T_{c}(P) displays an unusual M-shaped double dome with two maxima around P_{c1} and P_{c2}, respectively, leading to a tripled enhancement of T_{c} to about 8 K at 2 GPa. The obtained temperature-pressure phase diagram resembles those of unconventional superconductors, illustrating an intimated competition between CDW-like order and SC. The competition is found to be particularly strong for the intermediate pressure range P_{c1}≤P≤P_{c2} as evidenced by the broad superconducting transition and reduced superconducting volume fraction. The modification of CDW order around P_{c1} has been discussed based on the band structure calculations. This work not only demonstrates the potential to raise T_{c} of the V-based kagome superconductors, but also offers more insights into the rich physics related to the electron correlations in this novel family of topological kagome metals.

A recent focus of quantum spin liquid (QSL) studies is how disorder/randomness in a QSL candidate affects its true magnetic ground state. The ultimate question is whether the QSL survives disorder or the disorder leads to a “spin-liquid-like” state, such as the proposed random-singlet (RS) state. Since disorder is a standard feature of most QSL candidates, this question represents a major challenge for QSL candidates. YbMgGaO4, a triangular lattice antiferromagnet with effective spin-1/2 Yb3+ions, is an ideal system to address this question, since it shows no long-range magnetic ordering with Mg/Ga site disorder. Despite the intensive study, it remains unresolved as to whether YbMgGaO4 is a QSL or in the RS state. Here, through ultralow-temperature thermal conductivity and magnetic torque measurements, plus specific heat and DC magnetization data, we observed a residual κ0/T term and series of quantum spin state transitions in the zero temperature limit for YbMgGaO4. These observations strongly suggest that a QSL state with itinerant excitations and quantum spin fluctuations survives disorder in YbMgGaO4., It remains an open question as to whether the quantum spin liquid state survives material disorder, or is replaced by some spin-liquid like state. Here, Rao et al succeed in resolving a resolving a κ0/T residual in the thermal conductivity of YbMgGaO4 strongly suggesting the survival of the quantum spin liquid state.

The trilayer nickelate ${\mathrm{Nd}}_{4}{\mathrm{Ni}}_{3}{\mathrm{O}}_{10\ensuremath{-}\ensuremath{\delta}}$ was investigated by the measurements of x-ray diffraction, electrical resistivity, magnetic susceptibility, and heat capacity. The crystal structure data suggest a higher Ni valence in the inner perovskitelike layer. At ambient pressure the resistivity shows a jump at 162 K, indicating a metal-to-metal transition (MMT). The MMT is also characterized by a magnetic susceptibility drop, a sharp specific-heat peak, and an isotropic lattice contraction. Below $\ensuremath{\sim}50\phantom{\rule{0.28em}{0ex}}\mathrm{K}$, a resistivity upturn with $logT$ dependence shows up, accompanied with negative thermal expansion. External hydrostatic pressure suppresses the resistivity jump progressively, coincident with the weakening of the $logT$ behavior. The low-temperature electronic specific-heat coefficient is extracted to be $\ensuremath{\sim}150\phantom{\rule{0.28em}{0ex}}\mathrm{mJ}\phantom{\rule{0.28em}{0ex}}{\mathrm{K}}^{\ensuremath{-}2}\phantom{\rule{0.16em}{0ex}}\mathrm{mol}\text{\ensuremath{-}}{\mathrm{f}.\mathrm{u}.}^{\ensuremath{-}1}$, equivalent to $\ensuremath{\sim}50\phantom{\rule{0.28em}{0ex}}\mathrm{mJ}\phantom{\rule{0.28em}{0ex}}{\mathrm{K}}^{\ensuremath{-}2}\phantom{\rule{0.16em}{0ex}}\mathrm{mol}\text{\ensuremath{-}}{\mathrm{Ni}}^{\ensuremath{-}1}$, indicating an unusual heavy-electron correlated state. The novel heavy-electron state as well as the logarithmic temperature dependence of resistivity is explained in terms of the ${\mathrm{Ni}}^{3+}$-centered Kondo effect in the inner layer of the ${({\mathrm{NdNiO}}_{3})}_{3}$ trilayers.

The specific heat of single-crystal PrMnO

The magnetic Weyl semimetal $\mathrm{C}{\mathrm{o}}_{3}\mathrm{S}{\mathrm{n}}_{2}{\mathrm{S}}_{2}$ exhibits large anomalous Hall effect (AHE) due to its nontrivial band topology with enhanced Berry curvature. Here we investigate the pressure effect on the AHE of $\mathrm{C}{\mathrm{o}}_{3}\mathrm{S}{\mathrm{n}}_{2}{\mathrm{S}}_{2}$ up to 12 GPa with a palm cubic anvil cell apparatus and first-principles calculations simulation. We find that both the ferromagnetic transition temperature and the AHE are suppressed monotonically upon the application of high pressure. Data analyses revealed that in the investigated pressure range the intrinsic mechanism due to Berry curvature dominates the AHE as reflected by the validation of ${\ensuremath{\rho}}_{xy}^{A}\ensuremath{\propto}{\ensuremath{\rho}}_{xx}^{2}$. However, both the anomalous Hall conductivity and anomalous Hall angle are reduced gradually into the regime for conventional ferromagnetic metals with trivial band topology. Combined with theoretical calculations, our results indicate that the distance between Weyl points with opposite chirality in $\mathrm{C}{\mathrm{o}}_{3}\mathrm{S}{\mathrm{n}}_{2}{\mathrm{S}}_{2}$ is substantially reduced accompanying the suppression of ferromagnetism by pressure, thus providing an experimental route to tune the AHE of magnetic Weyl semimetals via modifying the nontrivial band topology.

We studied the magnetic properties of the garnet $\mathrm{C}{\mathrm{o}}_{3}\mathrm{A}{\mathrm{l}}_{2}\mathrm{S}{\mathrm{i}}_{3}{\mathrm{O}}_{12}$ synthesized under 5.5 GPa and 1250 \ifmmode^\circ\else\textdegree\fi{}C by means of dc magnetic susceptibility, neutron powder diffraction, and specific heat. Although the magnetic $\mathrm{C}{\mathrm{o}}^{2+}$ ions form a geometrically frustrated hyper-Kagome lattice, we find that $\mathrm{C}{\mathrm{o}}_{3}\mathrm{A}{\mathrm{l}}_{2}\mathrm{S}{\mathrm{i}}_{3}{\mathrm{O}}_{12}$ exhibits a long-range antiferromagnetic order below ${T}_{\mathrm{N}}=11\phantom{\rule{0.16em}{0ex}}\mathrm{K}$ without showing magnetic frustration, i.e., the frustration index $f\ensuremath{\equiv}|{\ensuremath{\theta}}_{\mathrm{CW}}/{T}_{N}|$ is close to unity. Refinements from neutron-diffraction data show that $\mathrm{C}{\mathrm{o}}_{3}\mathrm{A}{\mathrm{l}}_{2}\mathrm{S}{\mathrm{i}}_{3}{\mathrm{O}}_{12}$ forms a complex antiferromagnetic structure characterized by the coexistence of collinear and commensurate spiral magnetic ordering of $\mathrm{C}{\mathrm{o}}^{2+}$ sublattices. Magnetic field induced spin-flop transition at ${\ensuremath{\mu}}_{0}{H}_{c}\ensuremath{\approx}4\mathrm{T}$ was also observed below ${T}_{\mathrm{N}}$.

LiOsO3 is a strongly correlated metal that undergoes a nonpolar to polar transition at the critical temperature (T s) of 140 K. Complementary to previous studies of structure, Raman, and resistivity under high pressure (P), here we map out a complete pressure evolution of T s(P) via high-pressure resistance measurements up to 18.5 GPa by using a low-temperature multianvil apparatus. Our results show that T s(P) first increases linearly with pressure at a large slope as reported and then levels off gradually at pressures above 10 GPa when approaching room temperature (295 K). Interestingly, we find that the resistance R(T) of LiOsO3 at 18.5 GPa in the polar R3c phase exhibits a distinct temperature profile in comparison with those at lower pressures, signaling the possible occurrence of pressure-driven new electronic phase. The critical pressure for this transition is determined to be P c ≈ 16.8(1) GPa based on the pressure-dependent resistance measurement at room temperature.

A fundamental issue concerning iron-based superconductivity is the roles of electronic nematicity and magnetism in realising high transition temperature ($T_{\rm c}$). To address this issue, FeSe is a key material, as it exhibits a unique pressure phase diagram involving nonmagnetic nematic and pressure-induced antiferromagnetic ordered phases. However, as these two phases in FeSe overlap with each other, the effects of two orders on superconductivity remain perplexing. Here we construct the three-dimensional electronic phase diagram, temperature ($T$) against pressure ($P$) and isovalent S-substitution ($x$), for FeSe$_{1-x}$S$_{x}$, in which we achieve a complete separation of nematic and antiferromagnetic phases. In between, an extended nonmagnetic tetragonal phase emerges, where we find a striking enhancement of $T_{\rm c}$. The completed phase diagram uncovers two superconducting domes with similarly high $T_{\rm c}$ on both ends of the dome-shaped antiferromagnetic phase. The $T_{\rm c}(P,x)$ variation implies that nematic fluctuations unless accompanying magnetism are not relevant for high-$T_{\rm c}$ superconductivity in this system., 8 pages, 9 figures. A revised version will appear in Nature Communications

We report a thorough study of ${\mathrm{Y}}_{0.7}{\mathrm{La}}_{0.3}{\mathrm{VO}}_{3}$ single crystals by measuring magnetic properties, specific heat, thermal conductivity, Raman scattering, x-ray and neutron diffraction with the motivation of revealing the lattice response to the spin-orbital entanglement in $R{\mathrm{VO}}_{3}$. Upon cooling from room temperature, the orbitally disordered paramagnetic state changes around ${T}^{*}\ensuremath{\sim}220$ K to a spin-orbital entangled state which is then followed by a transition at ${T}_{N} = 116$ K to $C$-type orbital-ordered (OO) and $G$-type antiferromagnetic ordered (AF) ground state. In the temperature interval ${T}_{N}lTl{T}^{*}$, the ${\mathrm{VO}}_{6/2}$ octahedra have two comparable in-plane V-O bonds which are longer than the out-of-plane V-O1 bond. This octahedral site distortion supports the spin-orbital entanglement of partially filled and degenerate yz/zx orbitals. However, this distortion is incompatible with the steric octahedral site distortion intrinsic to orthorhombic perovskites. Their competition induces a second-order transition from the spin-orbital entangled state to a $C$-OO/$G$-AF ground state where the long-range OO suppresses the spin-orbital entanglement. Our analysis suggests that the spin-orbital entangled state and $G$-OO are comparable in energy and compete with each other. Rare-earth site disorder favors the spin-orbital entanglement rather than a cooperative Jahn-Teller distortion. The results also indicate for ${\mathrm{LaVO}}_{3}$ a $C$-OO/$G$-AF state in ${T}_{t} \ensuremath{\le} T \ensuremath{\le}{T}_{N}$ and an orbital flipping transition at ${T}_{t}$.

The $n$-type ${\text{HgCr}}_{2}{\mathrm{Se}}_{4}$ exhibits a sharp semiconductor-to-metal transition (SMT) in resistivity accompanying the ferromagnetic order at ${T}_{C}=106\text{ }\text{ }\mathrm{K}$. Here, we investigate the effects of pressure and magnetic field on the concomitant SMT and ferromagnetic order by measuring resistivity, dc and ac magnetic susceptibility, as well as single-crystal neutron diffraction under various pressures up to 8 GPa and magnetic fields up to 8 T. Our results demonstrate that the ferromagnetic metallic ground state of $n$-type ${\text{HgCr}}_{2}{\mathrm{Se}}_{4}$ is destabilized and gradually replaced by an antiferromagnetic, most likely a spiral magnetic, and insulating ground state upon the application of high pressure. On the other hand, the application of external magnetic fields can restore the ferromagnetic metallic state again at high pressures, resulting in a colossal magnetoresistance (CMR) as high as $\ensuremath{\sim}\text{ }3\ifmmode\times\else\texttimes\fi{}{10}^{11}%$ under 5 T and 2 K at 4 GPa. The present study demonstrates that $n$-type ${\text{HgCr}}_{2}{\mathrm{Se}}_{4}$ is located at a peculiar critical point where the balance of competition between ferromagnetic and antiferromagnetic interactions can be easily tipped by external stimuli, providing a new platform for achieving CMR in a single-valent system.

We have synthesized the high-pressure form of $\mathrm{CrS}{\mathrm{b}}_{2}$ with $\mathrm{CuA}{\mathrm{l}}_{2}$-type structure under 7 GPa and 700 \ifmmode^\circ\else\textdegree\fi{}C, and characterized its structural, transport, and magnetic properties by a suite of measurement techniques over a broad range of temperature, magnetic field, and pressure. In addition to previously reported ferromagnetic (FM) transition at ${T}_{\mathrm{C}}\ensuremath{\approx}160$ K, we discover another antiferromagnetic spin-density-wave (SDW) transition at ${T}_{\mathrm{s}}\ensuremath{\approx}90$ K, which is characterized by FM sheets of spins in the $ab$ plane that vary along the $c$ axis as determined by neutron powered diffraction. Pronounced anomalies around these two magnetic transitions are visible only in the lattice parameter $c$, signaling a strong spin-lattice coupling along the -Cr-Cr-Cr- infinite linear chain. We find that the application of magnetic field can suppress the SDW phase and stabilize the FM state down to the lowest temperature above ${\ensuremath{\mu}}_{0}{H}_{\mathrm{c}}\ensuremath{\approx}3$ T, around which a peculiar non-Fermi-liquid behavior with reduced effective mass emerges. On the other hand, the application of high pressure induces complex evolution of the magnetic states, i.e., the FM order is lowered while the SDW order is enhanced quickly until they merge together into a single antiferromagnetic transition, which is suppressed completely at ${P}_{\mathrm{c}}\ensuremath{\approx}9$ GPa. We observe near ${P}_{\mathrm{c}}$ non-Fermi-liquid behavior and enhancement of effective mass, which indicates the possible occurrence of magnetic quantum critical point. No superconductivity was observed down to 2 K around ${P}_{\mathrm{c}}$.

The orthorhombic perovskite iridate ${\mathrm{SrIr}}_{0.8}{\mathrm{Sn}}_{0.2}{\mathrm{O}}_{3}$ is reported to be a new candidate of Slater insulator at low temperatures. Here, we present optical spectroscopy measurements on ${\mathrm{SrIr}}_{0.8}{\mathrm{Sn}}_{0.2}{\mathrm{O}}_{3}$ at different temperatures ($T$) across the paramagnetic-antiferromagnetic phase transition. The low energy reflectivity decreases with reducing $T$. Six phonon peaks in the spectrum at low $T$ are visible at room temperature, indicating the absence of crystal structure phase transition from 300 K to 10 K. The real part of conductivity spectra ${\ensuremath{\sigma}}_{1}(\ensuremath{\omega})$ are obtained by employing the standard Kramers-Kronig transformation. In the paramagnetic state at room temperature, ${\ensuremath{\sigma}}_{1}(\ensuremath{\omega})$ reaches a limiting value as $\ensuremath{\omega}\ensuremath{\rightarrow}0$, implying an electrical conducting state. Upon decreasing $T$, the low frequency ${\ensuremath{\sigma}}_{1}(\ensuremath{\omega})$ decreases and approaches zero with a concomitant opening of a direct gap. Detailed analysis of the low energy data shows that the gap opening is continuous and ${\ensuremath{\sigma}}_{1}(\ensuremath{\omega})$ at the low energy gap edge follows an unusual ${\ensuremath{\omega}}^{1/2}$ dependence at low temperatures which is remarkably similar to other Slater insulators, such as ${\mathrm{NaOsO}}_{3}$.

The n-type HgCr_{2}Se_{4} exhibits a sharp semiconductor-to-metal transition (SMT) in resistivity accompanying the ferromagnetic order at T_{C}=106 K. Here, we investigate the effects of pressure and magnetic field on the concomitant SMT and ferromagnetic order by measuring resistivity, dc and ac magnetic susceptibility, as well as single-crystal neutron diffraction under various pressures up to 8 GPa and magnetic fields up to 8 T. Our results demonstrate that the ferromagnetic metallic ground state of n-type HgCr_{2}Se_{4} is destabilized and gradually replaced by an antiferromagnetic, most likely a spiral magnetic, and insulating ground state upon the application of high pressure. On the other hand, the application of external magnetic fields can restore the ferromagnetic metallic state again at high pressures, resulting in a colossal magnetoresistance (CMR) as high as ∼ 3×10^{11}% under 5 T and 2 K at 4 GPa. The present study demonstrates that n-type HgCr_{2}Se_{4} is located at a peculiar critical point where the balance of competition between ferromagnetic and antiferromagnetic interactions can be easily tipped by external stimuli, providing a new platform for achieving CMR in a single-valent system.

Cerebral ischemia-reperfusion injury is a major public health concern that causes high rates of disability and mortality in adults. Microglial activation plays a crucial role in ischemic stroke-induced alteration of the immune microenvironment. However, the mechanism underlying the triggering of microglial activation by ischemic stroke remains to be elucidated. Previously, we demonstrated that the protein kinase Hippo/MST1 plays an important role in oxidative stress-induced cell death in mammalian primary neurons and that the protein kinase c-Abl phosphorylates MST1 at Y433, which increases MST1 kinase activity. Microglial activation has been implicated as a secondary detrimental cellular response that contributes to neuronal cell death in ischemic stroke. Here, we are the first, to our knowledge, to demonstrate that MST1 mediates stroke-induced microglial activation by directly phosphorylating IκBα at residues S32 and S36. We further demonstrate that Src kinase functions upstream of MST1-IκB signaling during microglial activation. Specific deletion of MST1 in microglia mitigates stroke-induced brain injury. Therefore, we propose that Src-MST1-IκB signaling plays a critical role in stroke-induced microglial activation. Together with our previous work demonstrating that MST1 is important for oxidative stress-induced neuronal cell death, our results indicate that MST1 could represent a potent therapeutic target for ischemic stroke.

When MgO+ZrO2 were used as a sintering aid to SiC ceramics, it was found that ZrO2 reacted with SiC and MgO to form ZrC and a magnesium silicate. This reaction may provide a new route to synthesize ZrC or prepare ZrC/SiC composites by reaction sintering using ZrO2, SiC, and MgO as starting materials. In the present work, formation process of the ZrC phase in the SiC–MgO–ZrO2 system was addressed. Subsolidus phase relations at 1550 °C of the SiC–MgO–ZrO2 system and the related SiC–SiO2–ZrC–ZrO2–MgO (Si–Zr–Mg–O–C) system were investigated.

Millimeter-sized ${\mathrm{MnBi}}_{2}{\mathrm{Te}}_{4}$ single crystals are grown out of a Bi-Te flux and characterized using magnetic, transport, scanning tunneling microscopy, and spectroscopy measurements. The magnetic structure of ${\mathrm{MnBi}}_{2}{\mathrm{Te}}_{4}$ below ${T}_{N}$ is determined by powder and single-crystal neutron diffraction measurements. Below ${T}_{N}$ = 24 K, ${\mathrm{Mn}}^{2+}$ moments order ferromagnetically in the $ab$ plane but antiferromagnetically along the crystallographic $c$ axis. The ordered moment is 4.04(13)${\ensuremath{\mu}}_{B}$/Mn at 10 K and aligned along the crystallographic $c$ axis in an A-type antiferromagnetic order. Below ${T}_{N}$, the electrical resistivity drops upon cooling or when going across the metamagnetic transition in increasing magnetic fields. A critical scattering effect is observed in the vicinity of ${T}_{N}$ in the temperature dependence of thermal conductivity, indicating strong spin-lattice coupling in this compound. However, no anomaly is observed in the temperature dependence of thermopower around ${T}_{N}$. Fine tuning of the magnetism and/or electronic band structure is needed for the proposed topological properties of this compound. The growth protocol reported in this work might be applied to grow high-quality crystals where the electronic band structure and magnetism can be finely tuned by chemical substitutions.

RbGd

The cubic pyrochlore $\mathrm{C}{\mathrm{d}}_{2}\mathrm{R}{\mathrm{u}}_{2}{\mathrm{O}}_{7}$ develops a metalliclike state below the antiferromagnetic transition at ${T}_{\mathrm{N}}\ensuremath{\approx}90\phantom{\rule{0.16em}{0ex}}\mathrm{K}$, in contrast to the sharp transition to an insulating state below ${T}_{\mathrm{N}}$ of the $5d$-analog ${\mathrm{Cd}}_{2}{\mathrm{Os}}_{2}{\mathrm{O}}_{7}$. We have synthesized polycrystalline $\mathrm{C}{\mathrm{d}}_{2}\mathrm{R}{\mathrm{u}}_{2}{\mathrm{O}}_{7}$ under high pressure, and investigated the responses of its electronic behavior to hydrostatic pressure and isovalent substitutions of ${\mathrm{Ca}}^{2+}$ for ${\mathrm{Cd}}^{2+}$. Three characteristic anomalies are identified in the electrical transport and magnetic properties of $\mathrm{C}{\mathrm{d}}_{2}\mathrm{R}{\mathrm{u}}_{2}{\mathrm{O}}_{7}$, signaling an intimate correlation between charge and spin degrees of freedom. Interestingly, we found that the metalliclike state of $\mathrm{C}{\mathrm{d}}_{2}\mathrm{R}{\mathrm{u}}_{2}{\mathrm{O}}_{7}$ below ${T}_{\mathrm{N}}$ is very fragile and can be suppressed by a small hydrostatic pressure of $\ensuremath{\le}1\phantom{\rule{0.16em}{0ex}}\mathrm{GPa}$ or substitution of 5--10% ${\mathrm{Ca}}^{2+}$ for ${\mathrm{Cd}}^{2+}$, resulting in a resistivity behavior similar to that of ${\mathrm{Cd}}_{2}{\mathrm{Os}}_{2}{\mathrm{O}}_{7}$. In addition, the resultant insulating state below ${T}_{\mathrm{N}}$ is very robust against pressure, and the resistivity evolves gradually into two distinct activated regions under higher pressures. We constructed a temperature-pressure phase diagram for $\mathrm{C}{\mathrm{d}}_{2}\mathrm{R}{\mathrm{u}}_{2}{\mathrm{O}}_{7}$ and discussed its peculiar metalliclike state in terms of the electronic itinerancy/localization dichotomy via side-by-side comparisons with the related compounds ${A}_{2}\mathrm{R}{\mathrm{u}}_{2}{\mathrm{O}}_{7}(A=\mathrm{Ca},\mathrm{Hg})$ and ${\mathrm{Cd}}_{2}{\mathrm{Os}}_{2}{\mathrm{O}}_{7}$. Our results demonstrate that these cubic $4d/5d$ pyrochlore oxides offer an important paradigm for studying the exotic physics of correlated electrons on the border of (de)localization in the presence of strong geometrical frustration.

Saltified rutin enhances microglial Aβ clearance, providing a potential therapeutic avenue for Alzheimer’s disease treatment., The accumulation of aggregated amyloid-β (Aβ) in the brain is the first critical step in the pathogenesis of Alzheimer’s disease (AD), which also includes synaptic impairment, neuroinflammation, neuronal loss, and eventual cognitive defects. Emerging evidence suggests that impairment of Aβ phagocytosis and clearance is a common phenotype in late-onset AD. Rutin (quercetin-3-rutinoside) has long been investigated as a natural flavonoid with different biological functions in some pathological circumstances. Sodium rutin (NaR), could promote Aβ clearance by increasing microglial by increasing the expression levels of phagocytosis-related receptors in microglia. Moreover, NaR promotes a metabolic switch from anaerobic glycolysis to mitochondrial OXPHOS (oxidative phosphorylation), which could provide microglia with sufficient energy (ATP) for Aβ clearance. Thus, NaR administration could attenuate neuroinflammation and enhance mitochondrial OXPHOS and microglia-mediated Aβ clearance, ameliorating synaptic plasticity impairment and eventually reversing spatial learning and memory deficits. Our findings suggest that NaR is a potential therapeutic agent for AD.

We report high-field magnetization study on the complex spin system $h\text{\ensuremath{-}}\mathrm{ErMn}{\mathrm{O}}_{3}$ and propose an explanation for the $c$-axis phase transitions observed at 0.8, 12, and 28 T based on an analysis of the magnetization jumps, the complete $H\text{\ensuremath{-}}T$ phase diagram and the irreducible representations of the $\mathrm{E}{\mathrm{r}}^{3+}$ ($2a$ and $4b$) spin structure. Our measurements reveal that magnetic reorientation of the representation ${\mathrm{\ensuremath{\Gamma}}}_{2}$ induces the magnetic transition at 12 T, i.e., from a one-third plateau phase to a fully polarized phase. The magnetic transition at 0.8 T and the anomaly at 28 T can be understood by magnetic reorientations of ${\mathrm{\ensuremath{\Gamma}}}_{1}\ensuremath{\rightarrow}{\mathrm{\ensuremath{\Gamma}}}_{2}$ and a reflection of the $\mathrm{M}{\mathrm{n}}^{3+}$ moments triggered by the $\mathrm{E}{\mathrm{r}}^{3+}$ spins in strong magnetic fields. These scenarios are in good agreement with the magnetization process perpendicular to the $c$ axis and the magnetic susceptibility results. These findings are helpful for a complete understanding of the magnetic phase transitions and the underlying physics in this family compounds.

A facile glycine-nitrate method was developed to prepare superfine W-Ni-Fe powders by using relevant salts as the main raw materials, glycine as an incendiary agent and water as solvent. Phase composition of the composite powders was identified by X-ray diffraction analysis. Morphology of the powder was characterized by transmission electron microscopy and scanning electronic microscopy. Chemical composition of the powders was characterized by energy dispersive spectrometry. The test results indicate that superfine 95 W-3.5Ni-1.5Fe powders with grain sizes of about 150 nm could be obtained with the glycine-nitrate process. The powders showed good sinterability. Relative density higher than 97% with grain sizes of about 2 μm were obtained when the powder compacts were sintered at 1450 °C, and the sintered density reaches 99.3% at a sintering temperature of 1500 °C. The sintered W-Ni-Fe alloys showed good mechanical properties.

We have synthesized the cation ordered rutile-type $\mathrm{C}{\mathrm{r}}_{2}\mathrm{Re}{\mathrm{O}}_{6}$ and $\mathrm{CrRe}{\mathrm{O}}_{4}$ under high-pressure and high-temperature conditions and performed detailed characterizations on their structural, transport, and magnetic properties via x-ray and neutron powder diffraction, resistivity, magnetic susceptibility, and specific heat measurements. $\mathrm{C}{\mathrm{r}}_{2}\mathrm{Re}{\mathrm{O}}_{6}$ crystallizes in the inverse trirutile structure with lattice parameters $a=b=4.552\phantom{\rule{0.16em}{0ex}}21(5)\phantom{\rule{0.16em}{0ex}}\AA{}$ and $c=8.8934(1)\phantom{\rule{0.16em}{0ex}}\AA{}$ in the space group $P{4}_{2}/mnm$. It undergoes a second-order antiferromagnetic transition at ${T}_{\mathrm{N}}\ensuremath{\approx}67\phantom{\rule{0.16em}{0ex}}\mathrm{K}$ with the magnetic structure described by the propagation vector $\mathbf{k}=[0.5,0,0.5]$. For $\mathrm{CrRe}{\mathrm{O}}_{4}$, it adopts a monoclinically distorted rutile-like structure with unit-cell parameters $a=9.3393(2)\phantom{\rule{0.16em}{0ex}}\AA{}$, $b=5.6869(1)\phantom{\rule{0.16em}{0ex}}\AA{}$, $c=4.6243(1)\phantom{\rule{0.16em}{0ex}}\AA{}$, and $\ensuremath{\beta}=92.043{(8)}^{\ensuremath{\circ}}$ in the space group $C2/m$. It also exhibits an antiferromagnetic order at ${T}_{\mathrm{N}}=98\phantom{\rule{0.16em}{0ex}}\mathrm{K}$ with the magnetic structure described by the propagation vector $\mathbf{k}=[1,0,0.5]$. Interestingly, a large paramagnetic Weiss temperature of ${\ensuremath{\theta}}_{\mathrm{CW}}=\ensuremath{-}478\phantom{\rule{0.16em}{0ex}}\mathrm{K}$ is evidenced from the Curie-Weiss fitting to the inverse magnetic susceptibility. The temperature dependence of resistivity \ensuremath{\rho}($T$) for both compounds can be described with Mott's variable range hopping mechanism in the one-dimensional model for $\mathrm{C}{\mathrm{r}}_{2}\mathrm{Re}{\mathrm{O}}_{6}$ and the three-dimensional model for $\mathrm{CrRe}{\mathrm{O}}_{4}$, respectively. For both compounds, a weak resistivity anomaly can be discerned around ${T}_{\mathrm{N}}$ from the temperature derivative curves, signaling the interplay of charge and spin degrees of freedom for these $3d$(Cr)-$5d$(Re) coupled electron systems.

We report a high-pressure study on the heavily electron doped $\mathrm{L}{\mathrm{i}}_{0.36}{(\mathrm{N}{\mathrm{H}}_{3})}_{y}\mathrm{F}{\mathrm{e}}_{2}\mathrm{S}{\mathrm{e}}_{2}$ single crystal by using a cubic anvil cell apparatus. The superconducting transition temperature ${T}_{c}\ensuremath{\approx}44\phantom{\rule{0.16em}{0ex}}\mathrm{K}$ at ambient pressure is first suppressed to below 20 K upon increasing pressure to ${P}_{c}\ensuremath{\approx}2\phantom{\rule{0.16em}{0ex}}\mathrm{GPa}$, above which the pressure dependence of ${T}_{c}(P)$ reverses and ${T}_{c}$ increases steadily to ca. 55 K at 11 GPa. These results thus evidence a pressure-induced second high-${T}_{c}$ superconducting (SC-II) phase in $\mathrm{L}{\mathrm{i}}_{0.36}{(\mathrm{N}{\mathrm{H}}_{3})}_{y}\mathrm{F}{\mathrm{e}}_{2}\mathrm{S}{\mathrm{e}}_{2}$ with the highest ${T}_{c}^{\mathrm{max}}\ensuremath{\approx}55\phantom{\rule{0.16em}{0ex}}\mathrm{K}$ among the FeSe-based bulk materials. Hall data confirms that in the emergent SC-II phase the dominant electron-type carrier density undergoes a fourfold enhancement and tracks the same trend as ${T}_{c}(P)$. Interestingly, we find a nearly parallel scaling behavior between ${T}_{c}$ and the inverse Hall coefficient for the SC-II phases of both $\mathrm{L}{\mathrm{i}}_{0.36}{(\mathrm{N}{\mathrm{H}}_{3})}_{y}\mathrm{F}{\mathrm{e}}_{2}\mathrm{S}{\mathrm{e}}_{2}$ and (Li,Fe)OHFeSe. The present study demonstrates that high pressure offers a distinctive means to further raise the maximum ${T}_{c}$ of heavily electron doped FeSe-based materials by increasing the effective charge-carrier concentration via a possible Fermi-surface reconstruction at ${P}_{c}$.

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