Magnetic and electronic properties of a topological nodal line semimetal candidate: HoSbTe

Abstract

We report the experimental and theoretical studies of a magnetic topological nodal line semimetal candidate HoSbTe. Single crystals of HoSbTe are grown from Sb flux, crystallizing in a tetragonal layered structure (space group: P4/nmm, no. 129), in which the Ho-Te bilayer is separated by the square-net Sb layer. The magnetization and specific heat present distinct anomalies at ~ 4 K related to an antiferromagnetic (AFM) phase transition. Meanwhile, with applying magnetic field perpendicular and parallel to the crystallographic c axis, an obvious magnetic anisotropy is observed. Electrical resistivity undergoes a bad-metal-like state below 200 K and reveals a plateau at about 8 K followed by a drop due to the AFM transition. In addition, with the first-principle calculations of band structure, we find that HoSbTe is a topological nodal line semimetal or a weak topological insulator with or without taking the spin-orbit coupling (SOC) into account, providing a new platform to investigate the interplay between magnetic and topological fermionic properties.

Revealing a charge-density-wave gap in the predicted weak topological insulator HoSbTe

“…1(a) and (b) display the temperature dependent resistivity ρ(T ) and magnetization χ(T ), respectively. Although we have measured ρ(T ) and χ(T ) up to a higher temperature, there is not much difference with the previous report [22]: ρ(T ) shows a broad hump around 200 K and χ(T ) follows the Curie-Wiess law down to at least 100 K; an antiferromagnetic phase transition occurs at around 4 K. In order to check if there are any other phase transitions that may lead to the "insulator to metal" change inferred by resistivity, the first-order derivatives dρ(T )/dT and dχ(T )/dT are calculated and displayed in the inset of Fig. 1(a) and (b), respectively.…”

“…Among these WHM materials HoSbTe was theoretically predicted to be a weak topological insulator [22], which is corroborated afterwards by angle-resolved photoemission spectroscopy (ARPES) experiments exhibiting energy gaps much larger than 200 meV along certain momentum directions [23]. However the temperature dependent resistivity of HoSbTe exhibits a broad hump-like feature at around 200 K, indicating a bad-metal-like state at low temperatures, the underlying physics of which is yet to be revealed [22].…”

“…Single crystalline HoSbTe samples were synthesized by Sbflux method [22]. The temperature dependent resistivity ρ(T ) and magnetization χ(T ) up to 350 K were measured in a Quantum Design physical property measurement system.…”

“…Among these WHM materials HoSbTe was theoretically predicted to be a weak topological insulator [22], which is corroborated afterwards by angle-resolved photoemission spectroscopy (ARPES) experiments exhibiting energy gaps much larger than 200 meV along certain momentum directions [23]. However the temperature dependent resistivity of HoSbTe exhibits a broad hump-like feature at around 200 K, indicating a bad-metal-like state at low temperatures, the underlying physics of which is yet to be revealed [22]. The 4 f electrons of Ho atoms are believed to be generally localized and far away from the Fermi level, but an extremely large Sommerfeld coefficient γ ∼ 382.2 mJ/mol −1 /K 2 is obtained by a specific heat measurement [22], which is much larger than that of CeSbTe (γ = 41 mJ/mol −1 /K 2 ) [20], and comparable to many typical heavy fermion materials like CeCoIn5 [24].…”

“…However the temperature dependent resistivity of HoSbTe exhibits a broad hump-like feature at around 200 K, indicating a bad-metal-like state at low temperatures, the underlying physics of which is yet to be revealed [22]. The 4 f electrons of Ho atoms are believed to be generally localized and far away from the Fermi level, but an extremely large Sommerfeld coefficient γ ∼ 382.2 mJ/mol −1 /K 2 is obtained by a specific heat measurement [22], which is much larger than that of CeSbTe (γ = 41 mJ/mol −1 /K 2 ) [20], and comparable to many typical heavy fermion materials like CeCoIn5 [24]. This seems to infer a very large Kondo hybridization strength and thus the itinerancy of the f electrons in HoSbTe.…”