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Two cobalt oxyfluoride antiferromagnets CoMOF5(pyz)(H2O)2 (M = Nb 1, Ta 2; pyz = pyrazine) have been synthesized via conventional hydrothermal methods and characterized by thermogravimetric (TGA) analysis, FTIR spectroscopy, electron spin resonance (ESR), magnetic susceptibility, and magnetization measurements at both static low field and pulsed high field. The single-crystal X-ray diffraction indicates both compounds 1 and 2 are isostructural and crystallize in the monoclinic space group C2/m with a two-dimensional Co2+ triangular lattice in the ab plane, separated by the nonmagnetic MOF5 (M = Nb 1, Ta 2) octahedra along the c-axis with large intertriangular-lattice Co···Co distance. Because of low dimensionality together with frustrated triangular lattice, compounds 1 and 2 exhibit no long-range antiferromagnetic order until ∼3.7 K. Moreover, a spin flop transition is observed in the magnetization curves at 2 K for both compounds, which is further confirmed by ESR spectra. In addition, the ESR spectra suggest the presence of a zero-field spin gap in both compounds. The high field magnetization measured at 2 K saturates at ∼7 T with Ms = 1.55 μB for 1 and 1.71 μB for 2, respectively, after subtracting the Van Vleck paramagnetic contribution, which is usually observed for Co2+ ions with pseudospin spin of 1/2 at low temperature. Powder-averaged magnetic anisotropy of g = 3.10 for 1 (3.42 for 2) and magnetic superexchange interaction J/kB = -3.2 K for 1 (-3.6 K for 2) are obtained.

Severe traumatic brain injuries (STBIs) cause 1/3-1/2 of trauma-related deaths. Tumor necrosis factor (TNF) receptor-associated factor NF-κB activator (TANK)-binding kinase 1 (TBK1) is a biomarker associated with inflammation, while inflammation is a key promoter of the TBI process.To investigate the clinical significance of TBK1 in STBI patients.The present prospective observational study included a total of 95 STBI cases diagnosed from October 2019 to October 2021. The values for optic nerve sheath diameter (ONSD) were determined under deep sedation using 2-dimensional gray scale ultrasound. Intracranial pressure (ICP) was also measured. Serum levels of TBK1 and inflammatory factors such as C-reactive protein (CRP), interleukin (IL)-1β and IL-6 were evaluated with enzyme-linked immunosorbent assay (ELISA). Clinical variables including pathological type, Glasgow Coma Scale (GCS) score, sequential organ failure assessment (SOFA) score, and Acute Physiology and Chronic Health Evaluation II (APACHE II) score were recorded.The levels of TBK1 in the deceased patients were remarkably lower than in the patients who survived. The IL-1β and IL-6 were markedly elevated in deceased patients compared with survivors, and negatively correlated with serum levels of TBK1. The ONSD and ICP values were significantly higher in the deceased patients than in the patients who survived and were positively correlated with each other, while both were negatively correlated with TBK1 levels. Patients with lower TBK1 expression showed significantly lower GCS scores, higher SOFA and APACHE II scores, as well as a higher 1-month mortality rate. The Kaplan-Meier curve showed that patients with higher TBK1 levels had a higher 1-month survival rate compared with the patients with lower TBK1 levels. Only TBK1 and ONSD were independent risk factors for 1-month mortality in STBI patients.Lower serum TBK1 levels are associated with higher inflammatory factors, higher ONSD and ICP levels, as well as a poorer prognosis in STBI patients.

We have successfully synthesized a new transition metal tellurate compound K2Cu2(Te2O5)(TeO3)2·2H2O. The compound crystallizes in the monoclinic crystal system with space group P21/c; the Te coordi...

It was recently demonstrated that introducing the shape anisotropy of a skyrmion is an alternative strategy for controlling the skyrmion Hall effect. For example, an elliptical skyrmion shows anisotropic motion under the applied driving force. Here, we study the fundamental properties of an elliptical skyrmion induced by uniaxial in-plane magnetic anisotropy. The dynamics of a skyrmion under various parameters, such as uniaxial in-plane magnetic anisotropy, interfacial Dzyaloshinskii-Moriya interaction, and the damping constant, are investigated, and we employ Thiele's theory and derive expressions for the velocity of the skyrmion that match very well with micromagnetic simulation results. We find that the skyrmion Hall angle can reach ${90}^{\ensuremath{\circ}}$ with the optimized angle between the in-plane easy axis and the current. Our results offer a potential application of racetrack memory based on skyrmions, and a type of racetrack configuration was designed.

We investigated the magnetic characteristics of Na

We perform the quantum magnetotransport measurements and first-principles calculations on high quality single crystals of SmAlSi, a new topological Weyl semimetal candidate. At low temperatures, SmAlSi exhibits large non-saturated magnetoresistance (MR)~5200% (at 2 K, 48 T) and prominent Shubnikov-de Haas (SdH) oscillations, where MRs follow the power-law field dependence with exponent 1.52 at low fields ({\mu}0H < 15 T) and linear behavior 1 under high fields ({\mu}0H > 18 T). The analysis of angle dependent SdH oscillations reveal two fundamental frequencies originated from the Fermi surface (FS) pockets with non-trivial {\pi} Berry phases, small cyclotron mass and electron-hole compensation with high mobility at 2 K. In combination with the calculated nontrivial electronic band structure, SmAlSi is proposed to be a paradigm for understanding the Weyl fermions in the topological materials., Comment: 15 pages, 7 figures

Two cobalt oxyfluoride antiferromagnets CoMOF

We have investigated the magnetic properties and the magnetocaloric effect of GdScO 3 single crystal. A paramagnetic-antiferromagnetic magnetic phase transition has been observed in GdScO 3 single crystal at low temperature, with Gd 3+ sublattice in [001] direction ( T N = 2.6 K) and [010] direction ( T N = 2.8 K). This compound shows noticeable giant magnetocaloric effect with the maximum value of magnetic entropy change that come up to 47.3 J/kg K in [001] direction and 52.5 J/kg K in [010] direction for a field change of 70 kOe around its Neel temperature. The large magnetocaloric effect is due to the localized 4 f moment of Gd 3+ ( J = S = 7/2) ions. Taking the interactions of the system into consideration, the magnetization and magnetic entropy change can both be well fitted by the molecular field theory based on mean field approximation. The giant magnetocaloric effect suggest that GdScO 3 could be a potential material for magnetic refrigeration in low-temperature region.

We have synthesized a new spin-1/2 antiferromagnet, Y2Cu7(TeO3)6Cl6(OH)2, via a traditional hydrothermal method. This compound crystallizes in the triclinic crystal system with space group P1. The magnetic ions constitute a two-dimensional layered lattice with a novel topological structure in which the Cu4 clusters make up distorted diamond chains along the a axis and these chains are connected by the Cu3 trimers. The magnetic susceptibility and specific heat measurements show that the compound is antiferromagnetically ordered at TN = 4.1 K. This antiferromagnetic ordering is further supported by electron spin resonance (ESR) data. The magnetization curve presents a field-induced metamagnetic transition at 0.2 T, followed by a magnetization plateau within a wide magnetic field range from 7 T to at least 55 T, which corresponds to 3/7 of the saturated magnetization with g = 2.15 obtained from ESR. The possible mechanism for the magnetization plateau is discussed.

Single crystal Na2Co2TeO6 has been successfully grown by self-flux method, and its lattice structure and basic magnetic properties were characterized. As determined by single crystal X-ray diffraction, Na2Co2TeO6 belongs to space group P6322 (182) with a = b = 5.2709(2) A, c = 11.2615(15) A, and V = 270.95 (4) A3, the crystal structure is a layered honeycomb formed by CoO6 octahedra and the TeO6 octahedra in the center of the honeycomb layers, and the NaO6 octahedra are between the honeycomb layers. Magnetic susceptibility measurements indicate that the single crystal sample displays a distinct anisotropic behavior and the spin parallels the honeycomb plane (ab-plane). In a lower temperature region, a series of antiferromagnetic-like (AFM-like) phase transitions were observed, which may result from the spin reorientation of Co2+ ions. The different magnetization behavior between the polycrystalline structure and the single crystal (with the magnetic field parallel to and perpendicular to the ab-plane) rev...

The Mn3+ doped single crystal samples CuFe1−xMnxO2 with x = 0.01, 0.03 and 0.05 were synthetic by floating zone method, and their magnetization and electric polarization were measured with static and pulsed high magnetic field up to 50 T in the temperature ranging from 2 to 300 K. A series of field-induced magnetic phase transitions and electric polarization, which show obviously anisotropy, were observed in all the doped samples, and their critical fields were directly related to the Mn3+ doping level. The pulsed high magnetic dielectric polarization measurements show that, in the ferroelectric incommensurate phase, the spontaneous electric polarization region is enhanced by the Mn3+ dopant. The impact of the Mn3+ substitution on magnetic and electric polarization behaviors may associate with the partial release of spin frustration in the CuFeO2. Based on the experimental results, the impact of Mn3+ doping on the magnetization and electric polarization behavior as well as their anisotropy are investigated and a detailed magnetic diagram are assumed.

Yb3+/Er3+ co-doped crystals show strong up-conversion luminescence and their temperature dependence of luminescence intensity enable the application of temperature sensors. Such sensors usually work at hundreds Kelvin with high sensitivity, while the sensors appropriate to very low temperatures are rarely reported. In this study, we report the low temperature sensing of Gd3Ga5O12:Yb3+/Er3+ nanocrystals by partial or total substitution of Ga3+ by Fe3+. The up-conversion photoluminescence of the nanocrystals is measured on cooling from 300 to 4.2 K. The low-temperature sensing performance is improved, and the structure, magnetic and optical properties are modulated by the substitution of Fe3+ ions, rendering the nanocrystal useful for multi-functional sensing application.

A one-dimensional (1D) coordination polymer, [{Co2(pymca)2·(H2O)4}SO4·2H2O]n (1) (pymca = 2-carboxypyrimidine), was solvothermally synthesized via the reaction of 2-cyanopyrimidine and Co(SCN)2. A bidentate pymca ligand was formed in situ by the hydrolysis of 2-cyanopyrimidine. Furthermore, in this study, the magnetic properties of complex 1 were investigated in detail. The results indicated that complex 1 showed a single-chain magnet (SCM) behavior below ca. 3 K. The energy barrier (Δτ1/kB) and preexponential factor (τ0) of SCM were 31.2 K and 5.4 × 10−9 s, respectively.

Intrinsic antiferromagnetism in van der Waals (vdW) monolayer (ML) crystals enriches our understanding of two-dimensional (2D) magnetic orders and presents several advantages over ferromagnetism in spintronic applications. However, studies of 2D intrinsic antiferromagnetism are sparse, owing to the lack of net magnetisation. Here, by combining spin-polarised scanning tunnelling microscopy and first-principles calculations, we investigate the magnetism of vdW ML CrTe2, which has been successfully grown through molecular-beam epitaxy. We observe a stable antiferromagnetic (AFM) order at the atomic scale in the ML crystal, whose bulk is ferromagnetic, and correlate its imaged zigzag spin texture with the atomic lattice structure. The AFM order exhibits an intriguing noncollinear spin reorientation under magnetic fields, consistent with its calculated moderate magnetic anisotropy. The findings of this study demonstrate the intricacy of 2D vdW magnetic materials and pave the way for their in-depth analysis., In two dimensions magnetic order without magnetic anisotropy is forbidden, making 2D magnetic systems a rich playground for interesting physics. Here, Xian et al. fabricate monolayers of CrTe2, and demonstrate antiferromagnetic ordering, with spin reorientation at finite magnetic fields.

With the intention to explore excellent magnetocaloric materials, the intermetallic compound GdPd was synthesized by arc melting and heat treatment. The microstructure, magnetic and magnetocaloric properties of the intermetallic compound of GdPd were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and the physical property measurement system (PPMS). A large reversible magnetocaloric effect is observed in GdPd accompanied by a second order magnetic phase transition from paramagnetism to ferromagnetism at ∼39 K. The paramagnetic Curie temperature (θp) and the effective magnetic moment (μeff) are determined to be 34.7 K and 8.12 μB/Gd, respectively. The maximum entropy change ( | Δ S M Max | ) and the relative cooling power (RCP) under a field change of 5 T are estimated to be 20.14 J/(kg·K) and 433 J/kg, respectively. The giant reversible magnetocaloric effects (both the large ΔSM and the high RCP) together with the absence of thermal and field hysteresis make the GdPd compound an attractive candidate for low-temperature magnetic refrigeration.

Topological metals, including Dirac and Weyl semimetals, represent a wide class of quantum materials with non-trivial electronic band structures. The essential properties of Dirac or Weyl fermions, including light effective mass and high mobility, have been observed in a number of semimetal compounds, which in turn exhibit large positive magnetoresistances. Here, we report an unexpected observation of all these properties in α-gallium (α-Ga) single crystals, a pure metal that is in the liquid phase at room temperature and ambient pressure. Based on systematical transport measurements, α-Ga single crystal is found to exhibit large magnetoresistance, reaching about 1.66 × 106 per cent at 2 K in a magnetic field of 9 T. At low temperatures the de Haas–van Alphen and Shubinikov de Hass quantum oscillations show ultrahigh mobility and very small cyclotron effective mass for charge carriers, together with a non-trivial Berry phase. Combined with first-principle band structure calculations, these properties demonstrate α-Ga as a rare topological pure metal. Furthermore, superconductivity with Tc of ~0.9 K is confirmed by both specific heat and resistivity measurements. These findings suggest that α-Ga is a unique pure metal displaying both non-trivial topological and superconducting properties. A comprehensive investigation of bulk properties of α-Ga single crystals grown using a super cooled method—Ga is a metal that is liquid at room temperature—revealed that at very low temperatures this material exhibits a number of interesting properties; in particular, topology and superconductivity coexist. Bin Chen and colleagues measured a very large magnetoresistance, accompanied by a light effective mass and high mobility for the charge carriers, properties that suggest that the material is a topological metal. This conclusion is supported by first-principle calculations. Moreover, previous measurements indicating that the material is superconducting at very low temperature were experimentally confirmed. Materials exhibiting both topological properties and superconductivity provide a useful testing ground for understanding the interplay between superconducting pairing mechanisms and topology of the electronic band structure.

The structural, magnetic and magnetocaloric properties of Gd7Pd3- x Fe x compounds with x = 0, 0.2 and 0.4 were investigated. Rietveld refinement of X-ray powder diffraction shows that all the investigated samples are single phase and crystallize in a hexagonal structure with the space group P63mc. The lattice parameters (a, b and c), and the cell volume (v) decrease with the increase of Fe content in Gd7Pd3- x Fe x , mainly because of the difference in atomic radius between Fe and Pd. Magnetization versus temperature in a magnetic applied field of 0.05 T shows that Gd7Pd3- x Fe x displays a paramagnetic (PM) – ferromagnetic (FM) transition with the Curie temperature T C decreasing from 336 K for x = 0.0 to 319 K for x = 0.4. Under a field change of 0 to 5 T, the maximum values of the magnetic entropy change ( | Δ S M m a x | ) $\left( {|{\rm{\Delta }}S_M^{max}|} \right)$ are 5.09 J kg−1 K−1, 4.89 J kg−1 K−1, and 4.46 J kg−1 for x = 0, 0.2, and 0.4, and the corresponding relative cooling powers (RCP) amount to 387.6 J Kg−1, 357.2 J · Kg−1, and 385.5 J Kg−1, respectively. The stable magnetocaloric effect and refrigeration capacity near room temperature reveal that the Gd7Pd3- x Fe x compounds may be considered as refrigerants for magnetic refrigeration.

A new two-dimensional (2D) fluorophosphate compound Na3Cu5(PO4)4F·4H2O with a Cu5 cluster has been synthesized using a conventional hydrothermal method. The compound crystallizes in the orthorhombic crystal system with space group Pnma. The 2D layered structure is formed by cap-like {Cu5(PO4)4F} building units consisting of a Cu4O12F cluster plus a residual cap Cu2+ ion. Magnetic susceptibility exhibits a broad maximum at T2 = 19.2 K due to low-dimensional character followed by a long-range antiferromagnetic ordering at T1 = 11.5 K, which is further confirmed by the specific heat data. High-field magnetization measurement demonstrates a 2/5 quantum magnetization plateau above 40 T. The ESR data indicate the presence of magnetic anisotropy, in accordance with the 2D structure of the system.

CuFe0.99Mn0.01O2 and CuFe0.99Co0.01O2 single crystal samples are grown by a floating zone technique and their magnetization and spontaneous electric polarization have been investigated. Similarly with pure CuFeO2, an obviously anisotropic magnetization and spontaneous electric polarization were observed in the both doped samples, and their phase transition critical fields and temperatures are directly doping ion dependent. Considering the different d-shell configuration and ionic size between Mn3+, Co3+ and Fe3+ ions, in which the Mn3+ ion with Jahn-Teller (J-T) effect has different distortion on the geometry frustration from both of Fe3+ and Co3+ ion. Since for Mn3+ ion, the orbital splitting results from the low-symmetry J-T distortion in a crystal-field environment leads to a distorted MnO6 octahedron, which different from undistorted FeO6 and CoO6 octahedrons. The strain between distorted and undistorted octahedrons produces different effects on the spin reorientation transition and spontaneous electric polarization. Although the pure CuFeO2 has a very strong and robust frustration, the presence of the strain due to the random distribution of distorted MnO6 octahedron and undistorted CoO6 (FeO6) octahedrons leads to its spin reorientation transitions and spontaneous electric polarization different from CuFeO2.

Magnetic properties of La 1- x Sr x FeO 3 ( x = 0, 0.1, 0.2, 0.3, 0.4 and 0.5) have been investigated in a wide magnetic field range from 0 to 35 T using pulsed high magnetic field magnetization and electron spin resonance measurements. Experimental results show that both the non-magnetic Sr 2+ dopant and high magnetic fields affect the stability of the robust antiferromagnetic coupling between Fe ions and induce new phase transitions. Especially the phase transition temperatures and hysteresis behavior show a high sensitivity on the Sr dopant and its doping level. On the other hand, a nonlinear Sr doping level dependence of the transition temperatures and hysteresis behavior were observed, indicating that the charge disproportionation is not the sole influence. Thus, in the series Sr doping La 1- x Sr x FeO 3 samples, the dopant induced FeO 6 octahedron distortion and charge disproportionation are coexistence and competition, which leads to a complicated and Sr doping level nonlinearly dependent magnetization behavior.

Single-phase LaCr0.7Cu0.3O3 ceramics was fabricated successfully using high pressure sintering method. A mixed valent state with the coexistence of Cr2+，Cr3+ and Cr4+ was confirmed by X-ray photoelectron spectroscopy measurement. Magnetic measurement results indicate that in addition to antiferromagnetic superexchange interaction of Cr3+ -O2- -Cr3+ accompanied by weak ferromagnetism at high temperature, two types of short-range order ferromagnetism can be observed at low temperature, which could be attributed to double exchange interactions of Cr2+ -O2- -Cr3+ and Cr3+ -O2- -Cr4+, respectively. The results here would enrich the understanding on magnetic interactions in rare-earth chromites.

Recently, defect complex coupling in nonmagnetic acceptor-donor co-doped binary metal oxides is found to partially localize the donor electrons with a characteristic defect-dipolar freezing temperature (Tf) above which stable colossal permittivity (>103) persists. However, apart from a lot of co-doping cases, a clear idea of how to tailor the partial localisation behaviour is remain elusive. Here, based on phenomenological theories, we propose a spin-defect mediated partial localisation of donor electrons where the localisation behaviour can be tailored by the strength of exchange correlation between charge carrier spin and local spin. We found an ultrastable high-performance colossal permittivity behaviour over a broad frequency/temperature range in Co+Ta co-doped SnO2 with an unprecedentedly low Tf ( 150 K) and other doped binary metal oxides (> 7 K), pointing to a superstable large electronic moment of defect-dipole. The magnetic interactions between magnetic acceptor Co and donor ion significantly change the dielectric behaviour and magnetic order state, which modify the configurations of defect-dipolar clusters and change the partial localisation behaviour of donor electrons due to the exchange correlation between local spin from Co and charge carrier spin from donor. Despite the promising application potential of the novel dielectrics in cryogenic and aerospace microelectronics, the work advances the dielectric physics and benefit the exploration of novel electronic state in metal oxides and semiconductors via defect-engineering.

This report is on strain control of magnetic order parameters in 50 nm epitaxial NiFe2O4 (NFO) films grown on (001), (110), and (111) SrTiO3 (STO) single-crystal substrates by pulsed laser deposition. The related in-plane strains for NFO films on (001), (110), and (111) STO substrates are found to be ―1.36 %, 1.35 %, and 1.52 %, respectively, where the lattice mismatch between film and substrate is as high as 6.7 %. Our analysis of magnetization and ferromagnetic resonance on all the NFO films reveals the presence of a uniaxial anisotropy field, which is perpendicular to the film plane. The anisotropy field decreases with the increase of strain in NFO films. Specifically, NFO films on STO (111) and STO (001) have the lowest and highest uniaxial anisotropy fileds of 1.4 kOe and 6.1 kOe, respectively. These experimental values of anisotropy field are a factor of 5–10 times smaller than those of the calculated ones due to the film defects induced by the high lattice mismatch. The studies of magnetic anisotropy of spinel ferrite films are of interest for spintronics and microwave devices.