Unusual change in the Dirac-cone energy band upon a two-step magnetic transition in CeBi

Abstract

We have performed angle-resolved photoemission spectroscopy (ARPES) on CeBi which undergoes a two-step antiferromagnetic (AF) transition with temperature. Soft-x-ray ARPES has revealed the inverted band structure at the X point of bulk Brillouin zone for CeBi (and also for LaBi) as opposed to LaSb with non-inverted band structure. Low-energy ARPES on CeBi has revealed the Dirac-cone band at theΓ point in the paramagnetic phase associated with the bulk band inversion. On the other hand, a double Dirac-cone band appears on entering the first AF phase at T = 25 K, whereas a single Dirac-cone band recovers below the second AF transition at T = 14 K. The present result suggests an intricate interplay between antiferromagnetism and topological surface states in CeBi.

Anisotropic and extreme magnetoresistance in the magnetic semimetal candidate erbium monobismuthide

“…3(c) shows nonlinear field dependence even if the temperature warms up to 30 K, which suggests that the short range of magnetic orders persists to the temperature well above T N . The nonlinearity in magnetization below T N can be ascribed to the field-induced magnetic phase transitions, which has been commonly observed in RPn compound with partially filled f shell [10,12,15,16,21,25]. As shown in Fig.…”

“…Recent attention is given to the NaCl-type rare-earth monopnictide RPn (R = rare earth; Pn = Sb, Bi) family [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26], which are predicted to be promising correlated topological semimetal candidates [24,27]. RPn are always identified as compensated semimetals in the electronic structure aspect, where the conduction and valence bands are constituted by the 5d t 2g state of R and 3/2 p state of Pn, and lie at the X and points in the first Brillouin zone, respectively [28].…”

“…Once the 4 f shell of R ion is partially filled, the magnetic transitions could take place at low temperature (below the Néel temperature T N ), breaking the time-reversal symmetry and possibly yielding novel topological states with electronic correlations [24]. Strongly anisotropic magnetism and metamagnetic properties are always observed below T N in most of the magnetic RPn [10,12,15,16,21,25], which significantly affects the transport behaviors. Except for the plain parabolic field dependence, the extremely large magnetoresistance (MR) also shows turning points around the magnetic transitions in RPn (R = Ce, Nd, Dy, and Ho) with Ising-like spin states [10,12,15,16,21,25].…”

“…Strongly anisotropic magnetism and metamagnetic properties are always observed below TN in most of the magnetic RPn [10,12,15,16,21,25], which 4 significantly affects the transport behaviors. Except for the plain parabolic field dependence, the extremely large magnetoresistance (MR) also shows turning points around the magnetic transitions in RPn (R=Ce, Nd, Dy and Ho) with Ising-like spin states [10,12,15,16,21,25]. Intriguingly, orbital order is found to partially participate in the transport properties of some members with specific spin configurations.…”

Distinct topological properties in Ce monopnictides having correlated f electrons: CeN vs. CeBi

“…In addition, the double Dirac cones anticipated to be atM in Fig. 1(a), which are induced from band inversions at two nonequivalent bulk X points, would be gapped by their mutual hybridization, so as to lose their topological signature revealing trivial Rashba-type surface states [4,5].…”