Electronic structure of LaAgSb2 and CeAgSb2 studied by high-resolution angle-resolved photoemission spectroscopy

Arakane, T.; Sato, Takafumi; Souma, S.; Takahashi, Takashi; Watanabe, Yukio; Inada, Yuji

doi:10.1016/j.jmmm.2006.10.101

Cited by 20 publications

(18 citation statements)

References 5 publications

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“…As clearly apparent from Figure 16, the three FS sheets in CeAgAs 2 , possess a quasi-2D character in concert with the strong anisotropy of the physical properties of the compound. The 4-fold symmetry of the cylindrical sheets, characteristic of the tetragonal RETX 2 compounds [39,40] is approximately preserved (see Figure 16a,b), despite the small orthorhombic distortion present in CeAgAs 2 , and this finding supports the afore-made simplifications in the CEF analysis of the magnetic data of the compound (see above). Remarkably the two FS sheets displayed in Figure 16c exhibit apparent breaking of the 4-fold rotational symmetry into a two-fold one (nematic-like transition).…”

Section: Band Structure Calculationssupporting

confidence: 67%

Antiferromagnetic Ordering and Transport Anomalies in Single-Crystalline CeAgAs2

et al. 2020

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Single crystals of the ternary cerium arsenide CeAgAs2 were grown by chemical vapor transport. They were studied by means of x-ray diffraction, magnetization, heat capacity and electrical transport measurements. The experimental research was supplemented with electronic band structure calculations. The compound was confirmed to order antiferromagnetically at the Néel temperature of 4.9 K and to undergo metamagnetic transition in a field of 0.5 T at 1.72 K. The electrical resistivity shows distinct increase at low temperatures, which origin is discussed in terms of pseudo-gap formation in the density of states at the Fermi level and quantum corrections to the resistivity in the presence of atom disorder due to crystal structure imperfections.

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Section: Band Structure Calculationssupporting

confidence: 67%

Antiferromagnetic Ordering and Transport Anomalies in Single-Crystalline CeAgAs2

et al. 2020

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“…We note many such candidate materials indeed exist , e.g . ReAgSb 2 (Re = rare earth), for which small mass quasi-particles have been found 48 49 50 . Recent studies on LaAgSb 2 have shown its small mass quasi-particles indeed originate from the Dirac-cone like band structure formed by Sb 5 P x,y orbitals 51 .…”

Section: Resultsmentioning

confidence: 99%

Nearly massless Dirac fermions hosted by Sb square net in BaMnSb2

Liu

Cao

et al. 2016

Sci Rep

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Layered compounds AMnBi2 (A = Ca, Sr, Ba, or rare earth element) have been established as Dirac materials. Dirac electrons generated by the two-dimensional (2D) Bi square net in these materials are normally massive due to the presence of a spin-orbital coupling (SOC) induced gap at Dirac nodes. Here we report that the Sb square net in an isostructural compound BaMnSb2 can host nearly massless Dirac fermions. We observed strong Shubnikov-de Haas (SdH) oscillations in this material. From the analyses of the SdH oscillations, we find key signatures of Dirac fermions, including light effective mass (~0.052m0; m0, mass of free electron), high quantum mobility (1280 cm2V−1S−1) and a π Berry phase accumulated along cyclotron orbit. Compared with AMnBi2, BaMnSb2 also exhibits much more significant quasi two-dimensional (2D) electronic structure, with the out-of-plane transport showing nonmetallic conduction below 120 K and the ratio of the out-of-plane and in-plane resistivity reaching ~670. Additionally, BaMnSb2 also exhibits a G-type antiferromagnetic order below 283 K. The combination of nearly massless Dirac fermions on quasi-2D planes with a magnetic order makes BaMnSb2 an intriguing platform for seeking novel exotic phenomena of massless Dirac electrons.

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“…The Fermi surfaces of LaAgSb 2 have been studied by quantum oscillation measurements [9][10][11] combined with first-principles calculations and angle-resolved photoemission spectroscopy (ARPES) measurements [12,13]. Although several controversial conclusions can be seen in previous literature (e.g., regarding the shape of Fermi surfaces and correspondence of Fermi surface cross sections with quantumoscillation frequencies), LaAgSb 2 is considered to have four Fermi surfaces: two-hole Fermi surfaces around the point, a two-dimensional hollow electron surface, and an ellipsoidal electron surface around the X point [9].…”

Section: Introductionmentioning

confidence: 99%

Successive destruction of charge density wave states by pressure in LaAgSb2

et al. 2021

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We comprehensively studied the magnetotransport properties of LaAgSb 2 under high pressure up to 4 GPa, which showed unique successive charge density wave (CDW) transitions at T CDW1 ∼ 210 K and T CDW2 ∼ 190 K at ambient pressure. With the application of pressure, both T CDW1 and T CDW2 were suppressed and disappeared at the critical pressures of P CDW1 = 3.0-3.4 GPa and P CDW2 = 1.5-1.9 GPa, respectively. At P CDW1 , the Hall conductivity showed a steplike increase, which is consistently understood by the emergence of a two-dimensional hollow Fermi surface at P CDW1 . We also observed a significant negative magnetoresistance effect when the magnetic field and current were applied parallel to the c axis. The negative contribution was observed in the whole pressure region from 0 to 4 GPa. Shubnikov-de Haas (SdH) oscillation measurements under pressure directly showed the changes in the Fermi surface across the CDW phase boundaries. In P < P CDW2 , three major oscillation components, α, β, and γ , were identified, whose frequencies were increased by application of pressure. The increment rate of these frequencies was considerably larger than that expected from the shrinkage of lattice constant, indicating the unignorable band modification under pressure. In the normal metallic phase above P > P CDW1 , we observed a single frequency of ∼48 T with a cyclotron effective mass of 0.066m 0 , whose cross section in the reciprocal space corresponded to only 0.22% of the first Brillouin zone. Besides, we observed another oscillation component with frequency of ∼9.2 T, which is significantly enhanced in the limited pressure range of P CDW2 < P < P CDW1 . The amplitude of this oscillation was anomalously suppressed in the high-field and low-temperature region, which cannot be explained by the conventional Lifshitz-Kosevich formula.

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Electronic structure of LaAgSb2 and CeAgSb2 studied by high-resolution angle-resolved photoemission spectroscopy

Cited by 20 publications

References 5 publications

Antiferromagnetic Ordering and Transport Anomalies in Single-Crystalline CeAgAs2

Antiferromagnetic Ordering and Transport Anomalies in Single-Crystalline CeAgAs2

Nearly massless Dirac fermions hosted by Sb square net in BaMnSb2

Successive destruction of charge density wave states by pressure in LaAgSb2

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