arXiv subjects

Zhaoxu Chen

Publications and source records attributed to Zhaoxu Chen.

4 recordsLinked to original sources

arXiv2024

Fourfold Anisotropic Magnetoresistance and Unconventional Critical Exponents in Twinned FePd$_2$Te$_2$

As a special material symmetry operation, crystal twins usually influence physical properties. Here, detailed electrical transport and magnetic measurements were performed to reveal twinning effect on properties of van der Waals ferromagnet FePd$_2$Te$_2$. Orthorhombic crystal domains were observed in polarized optical microscopy and fixed $π$/2 angle between adjacent domains suggests a phase transition origin of the twins. FePd$_2$Te$_2$ exhibits fourfold in-plane anisotropic magnetoresistance. It is attributed to antiferromagnetic coupling component near atomically flat twin boundary and pseudo four-fold symmetry from perpendicular Fe chains. Intense magnetic domain motion is suggested by Hopkinson effect observed in magnetic susceptibility. A set of unusual critical exponents $β$ = 0.866, $γ$ = 1.043, $δ$ = 2.20 cannot be classified in any universal class predicted by renormalized group. Deviation from standard model reflects the non-saturating magnetization and slow growth of spontaneous magnetization resulting from crystal domain walls. These results show that additional symmetry from twins and twin boundary have a significant effect on electrical transport and magnetic properties of FePd$_2$Te$_2$. There is much room to modulate physical properties of twinned van der Waals ferromagnets through twins.

cond-mat.mtrl-sci↗

arXiv2024

Weakly Coupled Type-II Superconductivity in a Laves compound ZrRe2

We present a comprehensive investigation of the superconducting properties of ZrRe2, a Re-based hexagonal Laves compounds. ZrRe2 crystallizes in a C14-type structure (space group P63/mmc), with cell parameters a=b=5.2682(5) and c=8.63045 . Resistivity and magnetic susceptibility data both suggest that ZrRe2 exhibits a sharp superconducting transition above 6.1 K. The measured lower and upper critical fields are 6.27 mT and 12.77 T, respectively, with a large upper critical field that approached the Pauli limit.Measurements of the heat capacity confirm the presence of bulk superconductivity, with a normalized specific heat change of 1.24 and an electron-phonon strength of 0.69 . DFT calculations revealed that the band structure of ZrRe2 is intricate and without van-Hove singularity. The observed large specific heat jump, combined with the electron-phonon strength , suggests that ZrRe2 is a weakly coupled type II superconductor.

cond-mat.supr-con↗

arXiv2022

Delicate Superconductivity in NaAlGe Single Crystal

Nodal-line superconductor NaAlSi with a transition temperature ($T_c$) of 7 K has attracted considerable attention in recent years, whereas its Ge counterpart, NaAlGe, does not superconduct down to the lowest temperature regardless of their similar atomic and electrical structures. To tackle this enigma, we resort to the growth of NaAlGe single crystal and characterize its semimetallic ground state. Interestingly, when hole doped by oxidation, single-crystalline NaAlGe transforms from a semimetal to a superconductor ($T_c = 2.3 \sim$ 3.5 K) with zero resistivity and a diamagnetic shielding fraction over 100$\%$, but without a thermodynamic response in heat capacity. Continuous x-ray diffraction reveals a transient new structure with a larger $c$ axis, which is suggested to have arisen from the minor loss of Na and to be responsible for the emergence of the delicate superconductivity. Our findings resolve the controversies in NaAlSi and NaAlGe, while their similarities and differences provide an ideal opportunity to investigate a variety of exciting topological quantum states.

cond-mat.supr-con↗

arXiv2021

Discovery of two families of VSb-based compounds with V-kagome lattice

We report the structure and physical properties of two newly-discovered compounds AV8Sb12 and AV6Sb6 (A = Cs, Rb), which have C2 (space group: Cmmm) and C3 (space group: R-3m) symmetry, respectively. The basic V-kagome unit is present in both compounds, but stacking differently. A V2Sb2 layer is sandwiched between two V3Sb5 layers in AV8Sb12, altering the V-kagome lattice and lowering the symmetry of kagome layer from hexagonal to orthorhombic. In AV6Sb6, the building block is a more complex slab made up of two half-V3Sb5 layers that are intercalated by Cs cations along the c-axis. Transport property measurements demonstrate that both compounds are nonmagnetic metals, with carrier concentrations at around 1021cm-3. No superconductivity has been observed in CsV8Sb12 above 0.3 K under in-situ pressure up to 46 GPa. In contrast to CsV3Sb5, theoretical calculations and angle-resolved photoemission spectroscopy (ARPES) reveal a quasi-two-dimensional electronic structure in CsV8Sb12 with C2 symmetry and no van Hove singularities near the Fermi level. Our findings will stimulate more research into V-based kagome quantum materials.

cond-mat.supr-con↗