Pressure-induced topological phase transitions and strongly anisotropic magnetoresistance in bulk black phosphorus

Abstract

We report the anisotropic magneto-transport measurement on a non-compound band semiconductor black phosphorus (BP) with magnetic field B up to 16 Tesla applied in both perpendicular and parallel to electric current I under hydrostatic pressures. The BP undergoes a topological Lifshitz transition from band semiconductor to a zero-gap Dirac semimetal state, characterized by a weak localization-weak antilocaliation transition at low magnetic fields and the emergence of a nontrivial Berry Phase of π detected by SdH magneto-oscillations in magnetoresistance curves. In the transition region, we observe a pressure-dependent negative MR only in the B I configuration. This negative longitudinal MR is attributed to the Adler-Bell-Jackiw anomaly (topological E · B term) in the presence of weak antilocalization corrections.PACS numbers: 74.20. Rp, 74.25.Ha, 74.70.Dd More recently a new kind of topological materials termed Dirac or Weyl semimetal, three-dimensional (3D) analogs of two-dimensional graphene, has been intensively investigated both theoretically and experimentally in that Dirac or Weyl semimetal is a phase of matter that provides a solid state realization of chiral Weyl fermions [1][2][3][4][5][6][7][8]. Most of its unique physics is a consequence of chiral anomaly, namely non-conservation of the number of quasiparticles of a given chirality. This extraordinary property is notably characterised by a large and strongly anisotropic negative magneto-resistance (MR) which exists in the case when the electric and magnetic fields are collinearly aligned. Indeed, following the theoretical prediction, the chiral anomaly-induced negative MR has been notably realized in Dirac semimetal Cd 3 As 2 [9,10] Recently the narrow band-gap semiconductor, black phosphorus (BP), has been revived owing to the realization of mono-layered crystalline structure (phosphorene) and the exhibition of promising carrier mobilities, possible a new candidate for next-generation electronic and spintronic devices [20][21][22][23][24]. Fundamentally, BP has a relatively low band gap which can be further reduced by increasing the interlayer coupling. As its counterparts, slight change in the crystal structure thus strongly modifies the band gap of BP [25,26]. In particular, first-principle calculation predicts that BP posses a unique band structure, whose dispersion is nearly linear along the armchair direction [27,28]. Recent photoemission and magneto-transport measurements appear to support the theoretical prediction that bulk BP host 3D Dirac semimetal phase [29,30]. Therefore, in such Dirac semimetal of BP, there is strong interest in whether the chiral anomaly can be detected as a negative contribution to the longitudinal MR. In this paper we apply a moderate hydrostatic pressure to drive bulk BP into a semimetallic state. By anisotropic magnetoresistance measurements we observe a large negative MR only in the presence of electric and magnetic fields aligned collinearly. This negative longitudinal MR is attributed to the Adler-Bell-Jackiw ...

Pressure-induced phase transitions and superconductivity in a black phosphorus single crystal

“…The lack of inversion symmetry in the A17 phase converts the 2D Dirac semimetal into a Weyl semimetal (20). A negative magnetoresistance (MR) for B // I, consistent with the chiral anomaly characteristic of a Weyl semimetal, has indeed been reported in a high-pressure transport study (7). The Weyl semimetal phase of BP shows no sign of superconductivity down to 45 mK (21).…”

“…and report an extremely large MR effect and quantum Shubnikovde Haas (SdH) oscillations under high pressure (7,10,16,(19)(20)(21)(22)(23)(24)(25)(26). Superconductivity in BP occurring right after the A7 phase is induced at P ≥ 5 GPa (27)(28)(29).…”

“…Both highpressure phases are superconducting. Recent high-pressure studies with a piston-cylinder cell have revealed an interesting transition from semiconductor to topological semimetal within the A17 phase at P ∼ 1 GPa (7). However, the transitions to those highpressure phases occur at pressures out of the pressure range of the piston-cylinder devices (8); measurements of transport properties in the A7 and the C phases have been performed so far in a diamond anvil cell (DAC) and a multianvil device with a solid pressure-transmitting medium (9,10).…”

“…Hydrostatic pressure induces a Lifshitz-like semiconductorsemimetal transition at P ∼ 1 GPa by closing up the direct gap (19). Increasing pressure slightly further in a narrow pressure near 1.0 GPa or applying surface charges induces a topological transition with band inversion, which results in two Dirac points near the Z point (7,19,20). The lack of inversion symmetry in the A17 phase converts the 2D Dirac semimetal into a Weyl semimetal (20).…”

Origin of the pressure-dependent Tc valley in superconducting simple cubic phosphorus

“…Recently, topologically non-trivial semi-metallic properties have been discovered in the A17 structure at low pressure (i.e. a few GPa) [6][7][8][9] , which contributed to revitalizing the interest in this material. Under pressure, early studies showed that black phosphorus exhibits several phase transitions 1,2 .…”