Topology-Driven Magnetic Quantum Phase Transition in Topological Insulators

Zhang, Jinsong; Chang, Cui Zu; Tang, Peizhe; Zhang, Zuocheng; Feng, Xiao; Li, Kang; Wang, Li Li; Chen, Xi; Liu, Chaoxing; Duan, Wenhui; He, Ke; Xue, Qi Kun; Ma, Xu-Cun; Wang, Yayu

doi:10.1126/science.1230905

Cited by 229 publications

(250 citation statements)

References 38 publications

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“…Nevertheless, the QAHE was not observed in Mn-doped material, probably also because an increasing interstitial incorporation of Mn is observed with increasing doping concentration [12]. Cr remains the most promising dopant to achieve the QAHE [13], as it incorporates substitutionally on the Bi site [14] and leads to long-range ferromagnetic order at ∼8.5 K [15]. Recently, it has been shown that TIs proximity coupled to a ferrimagnetic insulator show an increased T C [16], suggesting the great potential of interface engineering to improve their magnetic properties.…”

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confidence: 99%

Magnetic proximity-enhanced Curie temperature of Cr-dopedBi2Se3thin films

et al. 2015

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We report a study on the transition temperature T C of Cr-doped topological insulator thin films, where an increase in the ferromagnetic onset can provide a pathway towards low-power spintronics in the future. Arrott plots, measured by surface-sensitive x-ray magnetic circular dichroism at the Cr L 2,3 edge as a function of field at various low temperatures, give a T C ≈ 7 K for the pristine surface. This is comparable to the bulk value of the film, which means that there is no indication that the spontaneous magnetization is different near the surface. Evaporation of a thin layer of Co onto the pristine surface of the in-situ cleaved sample increases the ordering temperature near the surface to ∼19 K, while in the bulk it rises to ∼10 K. X-ray absorption spectroscopy shows that Cr enters the Bi 2 Se 3 host matrix in a divalent state, and is unchanged by the Co deposition. These results demonstrate a straightforward procedure to increase the transition temperature of doped topological insulators.

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confidence: 99%

Magnetic proximity-enhanced Curie temperature of Cr-dopedBi2Se3thin films

et al. 2015

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“…But the electrical manipulation of magnetism in insulating MTIs has proved elusive. Recently, the magnetic ordering in TIs is shown to be related to the band topology [24], where the inverted band structure contributes a sizable Van Vleck magnetic susceptibility [6]. Here we propose the electric-field control of FM in an insulating MTI thin film.…”

mentioning

confidence: 99%

“…We consider in this Letter the m 0 = 0 case, where the band topology significantly affects the magnetism of the system [24] through the Van Vleck mechanism. In terms of the new basis the effective model becomes…”

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confidence: 99%

Electrically Tunable Magnetism in Magnetic Topological Insulators

2015

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The external controllability of the magnetic properties in topological insulators would be important both for fundamental and practical interests. Here we predict the electric-field control of ferromagnetism in a thin film of insulating magnetic topological insulators. The decrease of band inversion by the application of electric fields results in a reduction of magnetic susceptibility, and hence in the modification of magnetism. Remarkably, the electric field could even induce the magnetic quantum phase transition from ferromagnetism to paramagnetism. We further propose a transistor device in which the dissipationless charge transport of chiral edge states is controlled by an electric field. In particular, the field-controlled ferromagnetism in magnetic topological insulator can be used for voltage based writing of magnetic random access memories in magnetic tunnel junctions. The simultaneous electrical control of magnetic order and chiral edge transport in such devices may lead to electronic and spintronic applications for topological insulators. Introduction The recent discovery of the quantum anomalous Hall (QAH) effect has attracted intense interest in condensed matter physics [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. The QAH insulator is a new state of quantum matter which has a topologically nontrivial electronic structure characterized by a bulk energy gap but gapless chiral edge states, leading to the quantized Hall effect without an external magnetic field [16]. The edge channels of the QAH insulator conduct without dissipation, and thus has promising potential in the applications of low-power-consumption electronic devices. The QAH effect has been observed in thin films of Cr-doped [11-13] and V-doped [15] (Bi,Sb) 2 Te 3 magnetic topological insulators (MTIs), where robust bulk ferromagnetic (FM) ordering is spontaneously developed in this system even in the insulating regime.The ability to external control the magnetic properties of TIs [17][18][19] could be important both for fundamental and technological interest, particularly in view of recent developments in magnetoelectrics and spintronics [20,21]. In dilute FM semiconductors, the FM is mediated by itinerant charge carriers [22] and the magnetic ordering can be tuned by controlling the carrier density through an electric field [23]. But the electrical manipulation of magnetism in insulating MTIs has proved elusive. Recently, the magnetic ordering in TIs is shown to be related to the band topology [24], where the inverted band structure contributes a sizable Van Vleck magnetic susceptibility [6]. Here we propose the electric-field control of FM in an insulating MTI thin film. The band inversion is weakened by applying an electric field, leading to a reduction of the magnetic susceptibility, which is directly related to the magnetism. Remarkably, the electric field could even induce a quantum phase transition (QPT) from the FM phase to the paramagnetic (PM) phases. The thin film MTI with strong FM exhibits the QAH effect with chiral edg...

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“…In magnetically-doped Bi 2 Te 3 and Sb 2 Te 3 , both transport and magnetometry measurements have shown clear long-range FM order in several cases [6,7,55,58], which also resulted in the observation of QAHE [6,7]. The Zeeman gap opening at the Dirac point, however, has not been resolved by ARPES or scanning tunneling spectroscopy (STS), possibly due to their low T C and [59][60][61], are highly advantageous.…”

Section: The Pathways To Break the Time-reversal Symmetry In Tismentioning

confidence: 99%

“…Similar to conventional diluted magnetic semiconductors (DMSs) [46,47], impurity doping using transition metal (TM) elements (e.g., Cr, V, Mn) is a convenient approach to induce longrange FM order in TIs [48][49][50][51] [6,7,[51][52][53][54][55][56][57][58].…”

Section: The Pathways To Break the Time-reversal Symmetry In Tismentioning

confidence: 99%

Quantum anomalous Hall effect in time-reversal-symmetry breaking topological insulators

Chang

2016

J. Phys.: Condens. Matter

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101

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 2 observation of the QAHE in the above two systems, the current status of the research of the QAHE, and finally the prospects for future studies.Keywords: topological insulators (TIs), quantum anomalous Hall effect (QAHE), thin films, time-reversal symmetry (TRS), magnetic proximity effect. Content

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Topology-Driven Magnetic Quantum Phase Transition in Topological Insulators

Cited by 229 publications

References 38 publications

Magnetic proximity-enhanced Curie temperature of Cr-dopedBi2Se3thin films

Magnetic proximity-enhanced Curie temperature of Cr-dopedBi2Se3thin films

Electrically Tunable Magnetism in Magnetic Topological Insulators

Quantum anomalous Hall effect in time-reversal-symmetry breaking topological insulators

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