Magnetic and transport properties of Sb<sub>2</sub>Te<sub>3</sub> doped with high concentration of Cr

Gupta, Sachin; Kanai, Shun; Matsukura, F.; Ohno, Hideo

doi:10.7567/apex.10.103001

Cited by 18 publications

(15 citation statements)

References 31 publications

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“…Other theoretical works predict a dependence of the magnetic coupling on the precise configuration of the impurity 3d states [13][14][15][16][17][18] , as it is known in the context of dilute magnetic semiconductors [19][20][21][22][23][24] . Experimentally, the robustness of the FM state in Cr:(Bi,Sb) 2 Te 3 and V:(Bi,Sb) 2 Te 3 films was indeed found to vary substantially with dopant type and host stoichiometry 3,[25][26][27][28][29][30][31] . It was speculated that these variations arise from differences in the electronic structure of the two systems 3 .…”

Section: Introductionmentioning

confidence: 91%

Non-local effect of impurity states on the exchange coupling mechanism in magnetic topological insulators

et al. 2020

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Since the discovery of the quantum anomalous Hall (QAH) effect in the magnetically doped topological insulators (MTI) Cr:(Bi,Sb)2Te3 and V:(Bi,Sb)2Te3, the search for the magnetic coupling mechanisms underlying the onset of ferromagnetism has been a central issue, and a variety of different scenarios have been put forward. By combining resonant photoemission, X-ray magnetic circular dichroism and density functional theory, we determine the local electronic and magnetic configurations of V and Cr impurities in (Bi,Sb)2Te3. State-of-the-art first-principles calculations find pronounced differences in their 3d densities of states, and show how these impurity states mediate characteristic short-range pd exchange interactions, whose strength sensitively varies with the position of the 3d states relative to the Fermi level. Measurements on films with varying host stoichiometry support this trend. Our results explain, in an unified picture, the origins of the observed magnetic properties, and establish the essential role of impurity-state-mediated exchange interactions in the magnetism of MTI.

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Section: Introductionmentioning

confidence: 91%

Non-local effect of impurity states on the exchange coupling mechanism in magnetic topological insulators

et al. 2020

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“…1(b, c). The strong (00l) (l = 6,9,12,15,18) diffraction peaks ( Fig. 1(b, c)) indicate that the single crystal is a c-oriented crystal flake.…”

Section: Methodsmentioning

confidence: 98%

“…However, the onset temperature remains low, and it is widely believed that in-gap features are introduced by the transition metal dopant that are detrimental to performance. Therefore, magnetic doped TIs, e.g., V-, Cr-and Mn Sb2Te3 [7][8][9][10], Fe-and Mn-doped single crystals of Bi2Te3 [11,12] and Cr-, Mn-doped of Bi2Se3 [13,14], are being increasingly studied to determine the optimal set of dopants, magnetic order and transport properties in thin films and single crystals.…”

Section: Introductionmentioning

confidence: 99%

Quantum oscillations in iron-doped single crystals of the topological insulatorSb2Te3

et al. 2019

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We investigated the magnetotransport properties of Fe-doped topological insulator Sb1.96 Fe0.04Te3 single crystals. With doping, the band structure changes significantly and multiple Fermi pockets become evident in the Shubnikov-de Haas oscillations, in contrast to the single frequency detected for pure Sb2Te3. Using complementary density functional theory calculations, we identify an additional bulk hole pocket introduced at the Γ point which originates from the chemical distortion associated with the Fe-dopant. Experimentally, both doped and undoped samples are hole-carrier dominated, however, Fe doping also reduces the carrier density and mobility. The angle dependent quantum oscillations were analyzed to characterize the complex Fermi surface and isolate the dimensionality of each SdH feature. Among the components, at least two pockets possess 2D-like behavior according to their rotational dependence. These results indicate a complex interplay of hybridized dopant bands with the bulk and surface topological electronic structure.

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“…However, according to ab initio studies and corresponding experimental data, the superexchange in the case of V and Cr, and the RKKY coupling in Mn-doped films appear to contribute significantly to ferromagnetism in tetradymite V 2 -VI 3 compounds [71] . It appears that the co-existence of ferromagnetic superexchange with ferro-magnetic Bloembergen-Rowland and RKKY interactions accounts for T C as high as 250 K in (Cr x Sb 1−x ) 2 Te 3 with x = 0.44 [72] . Ferromagnetic coupling between magnetic impurities mediated by carriers residing in surface or edge Dirac cones is rather weak for realistic values of spatial extension of these states into the bulk [31] .…”

Section: Dilute Magnetic Topological Materialsmentioning

confidence: 99%

Families of magnetic semiconductors — an overview

2019

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The interplay of magnetic and semiconducting properties has been in the focus since more than a half of the century. In this introductory article we briefly review the key properties and functionalities of various magnetic semiconductor families, including europium chalcogenides, chromium spinels, dilute magnetic semiconductors, dilute ferromagnetic semiconductors and insulators, mentioning also sources of non-uniformities in the magnetization distribution, accounting for an apparent high Curie temperature ferromagnetism in many systems. Our survey is carried out from today's perspective of ferromagnetic and antiferromagnetic spintronics as well as of the emerging fields of magnetic topological materials and atomically thin 2D layers.The discovery of ferromagnetism in some europium chalcogenides and chromium spinels a half of the century ago [1] came as a surprise, since insulators typically showed antiferromagnetic or ferrimagnetic spin ordering, driven by a superexchange interaction, whereas ferromagnetism was considered a domain of metals. However, the Goodenough-Kanamori-Anderson rules indicate in which cases the superexchange can lead to ferromagnetic shortrange coupling between localized spins. This mechanism accounts e.g. for Curie temperature T C = 130 K in CdCr 2 Se 4 [2] . In the case of EuO and EuS, the antiferromagnetic superexchange is overcompensated by a direct f -d ferromagnetic exchange, which results in T C = 68 K and 16 K, respectively [3] .Soon after their discovery, magnetic semiconductors were found to exhibit outstanding properties, including *

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Magnetic and transport properties of Sb₂Te₃ doped with high concentration of Cr

Cited by 18 publications

References 31 publications

Non-local effect of impurity states on the exchange coupling mechanism in magnetic topological insulators

Non-local effect of impurity states on the exchange coupling mechanism in magnetic topological insulators

Quantum oscillations in iron-doped single crystals of the topological insulatorSb2Te3

Families of magnetic semiconductors — an overview

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Magnetic and transport properties of Sb2Te3 doped with high concentration of Cr

Cited by 18 publications

References 31 publications

Non-local effect of impurity states on the exchange coupling mechanism in magnetic topological insulators

Non-local effect of impurity states on the exchange coupling mechanism in magnetic topological insulators

Quantum oscillations in iron-doped single crystals of the topological insulatorSb2Te3

Families of magnetic semiconductors — an overview

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Magnetic and transport properties of Sb₂Te₃ doped with high concentration of Cr