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Unusual magnetic textures can be stabilized in f-electron materials due to the interplay between competing magnetic interactions, complex Fermi surfaces, and crystalline anisotropy. Here we investigate CeAuSb2, an f-electron incommensurate antiferromagnet hosting both single-Q and double-Q spin textures as a function of magnetic fields (H) applied along the c axis. Experimentally, we map out the field-temperature phase diagram via electrical resistivity and thermal expansion measurements. Supported by calculations of a Kondo lattice model, we attribute the puzzling magnetoresistance enhancement in the double-Q phase to the localization of the electronic wave functions caused by the incommensurate magnetic texture. The magnetic, electronic, and structural properties of a quantum material are intrinsically linked. In f-electron systems, such as cerium-based materials, this interplay can be exceedingly complex. Here, the authors investigate the antiferromagnet CeAuSb2 using a Kondo lattice model in order to resolve the changes in conductance that occur with variations in the magnetic spin texture as function of applied magnetic field.

The proposed topological Kondo insulator SmB$_{6}$ hosts a bulk Kondo hybridization gap that stems from strong electronic correlations and a metallic surface state whose effective mass remains disputed. Thermopower and scanning tunneling spectroscopy measurements argue for heavy surface states that also stem from strong correlations, whereas quantum oscillation and angle-resolved photoemission measurements reveal light effective masses that would be consistent with a Kondo breakdown scenario at the surface. Here we investigate the evolution of the surface state via electrical and thermoelectric transport measurements under hydrostatic pressure, a clean symmetry-preserving tuning parameter that suppresses the Kondo gap and increases the valence of Sm from 2.6+ towards a 3+ magnetic metallic state. Electrical resistivity measurements reveal that the surface carrier density increases with increasing pressure, whereas thermopower measurements show an unchanged Fermi energy under pressure. As a result, the effective mass of the surface state charge carriers linearly increases with pressure as the Sm valence approaches 3+. Our results are consistent with the presence of correlation-driven surface states in SmB$_{6}$ and suggest that the surface Kondo effect persists under pressure to 2 GPa.

CeIn

We report the dependence of antiferromagnetism on Zn-doping concentration in the newly synthesized $\mathrm{CeRh}{(\mathrm{I}{\mathrm{n}}_{1\text{\ensuremath{-}}x}\mathrm{Z}{\mathrm{n}}_{x})}_{5}$ single crystal with $x\ensuremath{\le}0.023$. X-ray-diffraction measurements showed a smooth decrease of lattice parameters with an increasing Zn concentration, indicating a positive chemical pressure effect. The electrical resistivity, specific heat, and magnetic susceptibility measurements revealed that the antiferromagnetic transition temperature ${T}_{\mathrm{N}}$ initially decreases from 3.8 K for pure $\mathrm{CeRhI}{\mathrm{n}}_{5}$ to 3.1 K at $x=0.012$; then, it becomes flat, remaining at approximately 3.1 K between Zn concentrations of 0.012 and 0.017, and finally, it increases to 3.3 K at 0.023 Zn concentration. These results suggest that the change in the electronic structure induced by Zn doping is more important than the chemical pressure effects with regard to tuning the magnetic order. A study on the electronic structure and pressure tuning of the newly synthesized heavy-fermion compound $\mathrm{CeRh}{(\mathrm{I}{\mathrm{n}}_{1\text{\ensuremath{-}}x}\mathrm{Z}{\mathrm{n}}_{x})}_{5}$, which does not include a toxic element, is expected to further enhance our understanding of the competing ground states emerging in heavy-fermion systems.

At ambient pressure and zero field, tetragonal CeAuSb$_{2}$ hosts stripe antiferromagnetic order at $T_{N} = 6.3$ K. Here we first show via bulk thermodynamic probes and x-ray diffraction measurements that this magnetic order is connected with a structural phase transition to a superstructure which likely breaks $C_{4}$ symmetry, thus signaling nematic order. The temperature-field-pressure phase diagram of CeAuSb$_{2}$ subsequently reveals the emergence of additional ordered states under applied pressure at a multicritical point. Our phenomenological model supports the presence of a vestigial nematic phase in CeAuSb$_{2}$ akin to iron-based high-temperature superconductors; however, superconductivity, if present, remains to be discovered.

We investigate the pressure and thermal annealing effects on BaFe

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

We report on an optical technique for measuring thermal expansion and magnetostriction at cryogenic temperatures and under applied hydrostatic pressures of 2.0 GPa. Optical fiber Bragg gratings inside a clamp-type pressure chamber are used to measure the strain in a millimeter-sized sample of CeRhIn5. We describe the simultaneous measurement of two Bragg gratings in a single optical fiber using an optical sensing instrument capable of resolving changes in length [dL/L = (L− L0)/L0] on the order of 10−7. Our results demonstrate the possibility of performing high-resolution thermal expansion measurements under hydrostatic pressure, a capability previously hindered by the small working volumes typical of pressure cells.