Both Electron and Hole Dirac Cone States inBa(FeAs)2Confirmed by Magnetoresistance

Abstract

Quantum transport of Dirac cone states in the iron pnictide Ba(FeAs)(2) with a d-multiband system is studied by using single crystal samples. Transverse magnetoresistance develops linearly against the magnetic field at low temperatures. The transport phenomena are interpreted in terms of the zeroth Landau level by applying the theory predicted by Abrikosov. The results of the semiclassical analyses of a two carrier system in a low magnetic field limit show that both the electron and hole reside as the high mobility states. Our results show that pairs of electron and hole Dirac cone states must be taken into account for an accurate interpretation in iron pnictides, which is in contrast with previous studies.

Two-Dimensional Massless Dirac Fermions in Antiferromagnetic AFe2As2 Chen1, Wang2, Song3 et al. 2017Phys. Rev. Lett.276220View full textAdd to dashboardCite

“…By fitting the ffiffiffi ffi B p dependence of the energies of T 1 and T 2 in case (ii) based on Eq. (3), we deduced υ F ≈ 1.18 × 10 5 m=s, which is comparable to the values reported by ARPES and transport measurements [28,30]. Therefore, T 1 and T 2 arise from the LL transitions, LL −1 → LL 0 and LL −1 → LL þ2 (or LL 0 → LL þ1 and LL −2 → LL þ1 ), respectively.…”

“…Therein, massless Kane fermions and Weyl fermions are characterized by a heavy-hole valence band around the band-degeneracy point and pairs of degenerate nodes with opposite chirality, respectively [35][36][37][38][39], while in PCIS, the heavy-hole valence band is absent and the degenerate nodes have the same chirality [19,20,28,31], which preclude the association of the observed linear band dispersions by ARPES with massless Kane fermions and Weyl fermions. Therefore, massless fermions in PCIS were suggested to be MDF [19,20,25,[28][29][30][31][32][33][34]. However, whether MDF in PCIS are 2D or 3D remains unclear.…”

“…Furthermore, angle-resolved photoemission spectroscopy (ARPES) measurements of BaFe 2 As 2 show linear band dispersions within k x -k y plane below E F [28]. Therefore, massless fermions, which are characterized by band-degeneracy points and linear energy-momentum dispersions, are expected to exist in the AFM state of BaFe 2 As 2 [19,20,25,[28][29][30][31][32][33][34]. There are three types of massless fermions, including MDF, massless Kane fermions, and Weyl fermions [35][36][37][38][39][40][41][42].…”

Suppression of backward scattering of Dirac fermions in iron pnictides Ba(Fe1−xRuxAs)Tanabe1, Huynh2, Urata3 et al. 2012Phys. Rev. B142180View full textAdd to dashboardCite

“…The value of dR M /dB developed linearly with B but was saturated above 2 T for x = 0, which indicates that the B dependence of R M from R M ∝ B 2 to R M ∝ B had changed. [12]. The crossover magnetic field (B * ) between R M ∝ B 2 and R M ∝ B increased with an increase in x, while its absolute value of dR M /dB decreased with an increase in x [26].…”

“…A Dirac cone characterized by a degeneracy point in the linear band dispersion is known to be realized in materials with special geometrical symmetries, such as the K-K' degenerate points in graphene [1], topological insulators (TIs) with the Z 2 symmetrical constraint [2], some organic conductors [3] with a degenerate crossing band, and iron pnictides with different d xy -d xz orbital symmetry [4][5][6][7][8][9][10][11][12][13][14][15][16]. One of the significant features of electronic transport in the Dirac cone states is the large suppression of backward scattering as a consequence of the Berry's phase.…”