Large power factor and anomalous Hall effect and their correlation with observed linear magneto resistance in Co-doped Bi₂Se₃3D topological insulator

Abstract

Magnetoresistance (MR), thermo power, magnetization and Hall effect measurements have been performed on Co-doped Bi2Se3 topological insulators. The undoped sample shows that the maximum MR as a destructive interference due to a π-Berry phase leads to a decrease of MR. As the Co is doped, the linearity in MR is increased. The observed MR of Bi2Se3 can be explained with the classical model. The low temperature MR behavior of Co doped samples cannot be explained with the same model, but can be explained with the quantum linear MR model. Magnetization behavior indicates the establishment of ferromagnetic ordering with Co doping. Hall effect data also supports the establishment of ferromagnetic ordering in Co-doped Bi2Se3 samples by showing the anomalous Hall effect. Furthermore, when spectral weight suppression is insignificant, Bi2Se3 behaves as a dilute magnetic semiconductor. Moreover, the maximum power factor is observed when time reversal symmetry (TRS) is maintained. As the TRS is broken the power factor value is decreased, which indicates that with the rise of Dirac cone above the Fermi level the anomalous Hall effect and linearity in MR increase and the power factor decreases.

Magnetization switching using topological surface states

“…One can see that (i) R H decreases linearly with an increase in the magnetic field ( H ), indicating the n-type nature of the Bi 2 Se 3 film, and (ii) the slope is larger at lower T . These characteristics are consistent with those reported previously for Bi 2 Se 3 films ( 19 ). Figure 1E presents the sheet carrier density ( n 2D ) calculated from the R H data; the calculation used n2normalD=−μ0HeRH ( 20 ), where μ 0 is the permeability of free space and − e is the elementary charge.…”

Growth, Characterization and High-Field Magneto-Conductivity of Co0.1Bi2Se3 Topological Insulator

“…can bring about magnetic ordering, which may further enable to observe different exotic phenomena such as anomalous quantized Hall (AQH) state, magnetic monopole, topological magneto electric effect and the Faraday-Kerr effects [14][15][16][17][18][19][20][21]. In this regards, till date, several studies have been reported, which addresses the effect of magnetic ordering in various TIs viz., ferromagnetism (FM) has been observed in Cr doped Bi 2 Te 3 and Bi 2 Se 3 thin film [22][23][24], Fe doped Bi 2 Se 3 nanoribbons [25,26], Mn and V doped Bi 2 Se 3 thin films [27,28], Co doped Bi 2 Se 3 [29][30][31][32][33], Mn and Ni doped Bi 2 Se 3 [34][35][36], Fe doped Bi 2 Te 3 [37], Mn doped bulk Bi 2 Te 3 [38] and Fe and Co doped Sb 2 Te 3 [39,40].…”

“…Among the various discovered TIs (Bi 1-x Sb x , Bi 2 Te 3 , Bi 2 Se 3 , Sb 2 Te 3 ), Bi 2 Se 3 is one of the most popular and widely studied 3D TI due to the presence of a single surface Dirac cone along with a large bulk band gap of 0.3eV, promising for room temperature applications [4,15]. Although Co doping has been done earlier in Bi 2 Se 3 [29][30][31][32][33],…”

Crossover from weak-antilocalization transport to quantum magnetoresistance of Dirac states in quenched Fe0.01Bi2Te3 single crystals with large magnetoresistance and high Hall mobility

“…To date, intense efforts have been made regarding intentional magnetic doping of topological semiconductors. Ferromagnetism of MTIs has been reported in Fe and Mn-doped Bi 2 Te 3 [3][4][5], Co and Fedoped Bi 2 Se 3 [6][7][8], Cr-doped Sb 2 Te 3 [9], and V-doped (Bi,Sb) 2 Te 3 [10]. In particular, the stability, electronic, and magnetic properties of the MTIs Bi 2 Se 3 , Bi 2 Te 3 , and Sb 2 Te 3 have been predicted and provided important guidance for magnetism incorporation in MTIs experimentally [11].…”