Pressure and inversion symmetry breaking field-driven first-order phase transition and formation of Dirac circle in perovskites

Kore, Ashish; Kashikar, Ravi; Gupta, Manish; Singh, Poorva; Nanda, B. R. K.

doi:10.1103/physrevb.102.035116

Cited by 12 publications

(18 citation statements)

References 41 publications

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“…This effect should be observable experimentally with the use of gate potentials. Similar discontinuous topological transitions might be possibly observed in other (non-superconducting) systems [12,51].…”

supporting

confidence: 77%

Unconventional topological transitions in a self-organized magnetic ladder

Maśka,

Sedlmayr,

Kobiałka

et al. 2021

Preprint

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It is commonly assumed that topological phase transitions in topological superconductors are accompanied by a closing of the topological gap or a change of the symmetry of the system. We demonstrate that an unconventional topological phase transition with neither gap closing nor a change of symmetry is possible. We consider a nanoscopic length ladder of atoms on a superconducting substrate, comprising self-organized magnetic moments coupled to itinerant electrons. For a range of conditions, the ground state of such a system prefers helical magnetic textures, selfsustaining topologically nontrivial phase (referred to as topofilia). Abrupt changes in the magnetic order as a function of induced superconducting pairing or chemical potential can cause topological phase transitions without closing the topological gap. Furthermore, the ground state prefers either parallel or anti-parallel configurations along the rungs, and the anti-parallel configuration causes an emergent time reversal asymmetry protecting Kramer's pair's of Majorana zero modes, but in a BDI topological superconductor. We determine the topological invariant and inspect the boundary Majorana zero modes.

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supporting

confidence: 77%

Unconventional topological transitions in a self-organized magnetic ladder

Maśka,

Sedlmayr,

Kobiałka

et al. 2021

Preprint

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“…When an organic molecule like CH 3 NH 3 replaces an inorganic element like Cs at the A site of ABX 3 , the inversion symmetry is broken to create a polarized electric field [22,23]. Duelling upon such intrinsic field, design principles have been developed for wider class of materials to create requisite field controlled and switchable spin texture [24,25].…”

Section: Introductionmentioning

confidence: 99%

“…In the equilibrium state, the valence band edge is formed by the B-s states while predominantly the Bp states constitute the three conduction bands. The Rashba spin orbit coupling breaks the Kramer degeneracy around the time reversal invariant momenta (TRIM) R. Under hyrdrostatic pressure, the top valence band and the bottom conduction band invert their orbital characters significantly to induce the TI phase [23]. The model Hamiltonian, appropriate to describe the band structure for the family of Halide perovskites, is formulated to be…”

Section: Introductionmentioning

confidence: 99%

“…The third and fourth terms of the Hamiltonian respectively represent the atomic spin-orbit coupling ( λ L • S) and polarized field (E P ) led spin-orbit coupling (α P ( ÊP × k) • σ). The value of λ is taken to be 0.5eV which is of the same order as seen in MAPbI 3 [23]. Here, α P is the coupling strength which is proportional to the strength of the field, and σ are the Pauli spin matrices.…”

Section: Introductionmentioning

confidence: 99%

“…4. For the field γ ẑ, two sets of Dirac cones interpenetrates to create a Dirac circle around the high symmetry point R. Without the field, these two sets coincide to create a four-fold degenerate Dirac node [19,20,23]. However, switching the direction of the field perpendicular to the growth direction, i.e.…”

Section: Introductionmentioning

confidence: 99%

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Spin Texture as Polarization Fingerprint of Halide Perovskites

Gupta,

Nanda

2021

Preprint

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Halide perovskites are perceived to be the promising class of materials for optoelectronics, spinorbitronics and topological electronics due to presence of strong spin-orbit coupling and polarized field. Here, we develop a Hamiltonian using quasi-degenerate perturbation theory to describe polarized field driven band structures and unique topological phases such as Dirac semimetallic rings for the universal class of Halide perovskites including both inorganic and hybrid members. The spin textures obtained through this theoretical model captures minute effects of polarization and hence can be used as a modern tool to determine the polarized field directions which have significant influence on spinorbitronics. The analysis brings out the concepts of hybrid spin textures intermixing the effects of valence and conduction bands under topological quantum phase transitions, and spin texture binaries where alignment of the spins are reversed between domains in the momentum space with sharp boundaries. The results are validated through density functional calculations.

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