Unusual valence state in the antiperovskites 
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>Sr</mml:mi><mml:mn>3</mml:mn></mml:msub><mml:mi>SnO</mml:mi></mml:math>
 and 
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>Sr</mml:mi><mml:mn>3</mml:mn></mml:msub><mml:mi>PbO</mml:mi></mml:mrow></mml:math>
 revealed by x-ray photoelectron spectroscopy

Huang, D.; Nakamura, H.; Küster, Kathrin; Yaresko, A. N.; Samal, D.; Schröter, Niels B. M.; Strocov, Vladimir N.; Starke, Ulrich; Takagi, H.

doi:10.1103/physrevmaterials.3.124203

Cited by 16 publications

(14 citation statements)

References 43 publications

(54 reference statements)

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“…Importantly, many antiperovskites are stable and experimentally well studied. In particular, the compounds Ca 3 PbO, Ca 3 SnO, Sr 3 PbO, and Sr 3 SnO have been the subject of several recent experiments [40][41][42][43][44][45][46]. Thus, our results present a promising avenue to pursue experimen- tal studies of HOTIs, for which very few other candidates have been identified.…”

Section: Discussionmentioning

confidence: 76%

Higher-order topological insulators in antiperovskites

Fang,

Cano

2020

Preprint

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We prove that a family of antiperovskite materials realize a higher order topological insulator (HOTI) phase, characterized by a previously introduced Z4 index. A tight binding model and a k • p model are used to capture the physics of the bulk, surface and hinge states of these materials. A phase diagram of the higher order and weak topological invariants is obtained for the tight binding model. The mirror Chern number is also discussed. In order to reveal the gapless hinge states in the presence of mirror Chern surface states, several ways of opening the surface gap are proposed and confirmed by calculation, including cleaving the crystal to reveal a low-symmetry surface, building a heterostructure, and applying strain. Upon opening the surface gap, we are able to study the hinge states by computing the momentum space band structure and real space distribution of mid-gap states.

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Section: Discussionmentioning

confidence: 76%

Higher-order topological insulators in antiperovskites

Fang,

Cano

2020

Preprint

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“…Detailed growth procedures, as well as film characterization via x-ray diffraction (XRD), low-energy electron diffraction and x-ray photoelectron spectroscopy, can be found in Refs. [39,40].…”

Section: Methodsmentioning

confidence: 99%

“…Line-cut analysis [Fig.2(c)] reveals step edges with heights corresponding to integer multiples of the unit cell (UC), roughly 0.51 nm. We were unable to resolve an atomic lattice, likely due to complications arising from surface polarity and valence instability[40].…”

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confidence: 99%

Planar Hall effect with sixfold oscillations in a Dirac antiperovskite

Huang,

Nakamura,

Takagi

2021

Preprint

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The planar Hall effect (PHE), wherein a rotating magnetic field in the plane of a sample induces oscillating transverse voltage, has recently garnered attention in a wide range of topological metals and insulators. The observed twofold oscillations in ρyx as the magnetic field completes one rotation are the result of chiral, orbital and/or spin effects. The antiperovskites A3BO (A = Ca, Sr, Ba; B = Sn, Pb) are topological crystalline insulators whose low-energy excitations are described by a generalized Dirac equation for fermions with total angular momentum J = 3/2. We report unusual sixfold oscillations in the PHE of Sr3SnO, which persisted nearly up to room temperature. Multiple harmonics (twofold, fourfold and sixfold), which exhibited distinct field and temperature dependencies, were detected in ρxx and ρyx. These observations are more diverse than those in other Dirac and Weyl semimetals and point to a richer interplay of microscopic processes underlying the PHE in the antiperovskites.

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“…ABX 3 perovskites, as the largest family of crystalline materials, also have their counterpart antistructures, A 3 BX antiperovskites 7 . In contrast to the perovskite compounds constructed by the ionic bonds of constituent elements in stable valence states, the antiperovskites have mixed bonding characters with ionic, covalent, and metallic bonds in unusual valence states 8 . However, oxide antiperovskites (A 3 BO), antistructures of common oxide perovskites (ABO 3 ), are hardly stabilized in ambient conditions as oxygen tends to form ionic bonds with counter-cationic A and B elements due to its large ionicity 9 .…”

Section: Introductionmentioning

confidence: 99%

Unusual d-electron heavy-fermion behaviour in f-electron ferromagnetic antiperovskite Gd3SnC

Bang

Park

Lee

et al. 2021

Preprint

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Inverted structures of common crystal lattices, referred to as antistructures, are rare in nature due to their thermodynamic constraints imposed by the switched cation and anion positions in reference to the original structure. However, a stable antistructure formed with mixed bonding characters of constituent elements in unusual valence states can provide unexpected material properties. Here, we report a heavy-fermion behaviour of ferromagnetic gadolinium lattice in Gd3SnC antiperovskite, contradicting the common belief that ferromagnetic gadolinium cannot be a heavy-fermion system. The specific heat shows an unusually large Sommerfeld coefficient of ~ 1114 mJ⋅mol− 1⋅K− 2 with a logarithmic behaviour of non-Fermi-liquid state. We demonstrate that the heavy-fermion behaviour in the non-Fermi-liquid state appears to arise from the hybridized electronic states of gadolinium 5d-electrons participating in metallic Gd–Gd and covalent Gd–C bonds. These results accentuate unusual chemical bonds in CGd6 octahedra with the dual characters of gadolinium 5d-electrons for the emergence of heavy-fermions.

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Unusual valence state in the antiperovskites Sr3SnO and Sr3PbO revealed by x-ray photoelectron spectroscopy

Cited by 16 publications

References 43 publications

Higher-order topological insulators in antiperovskites

Higher-order topological insulators in antiperovskites

Planar Hall effect with sixfold oscillations in a Dirac antiperovskite

Unusual d-electron heavy-fermion behaviour in f-electron ferromagnetic antiperovskite Gd3SnC

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