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Saito, H.; Zayets, V.; Yamagata, S.; Ando, Koji

doi:10.1103/physrevlett.90.207202

Cited by 415 publications

(199 citation statements)

References 31 publications

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“…11 Since the ferromagnetic MCD signal of Co 2+ : ZnO did not resemble that of paramagnetic Co 2+ : ZnO and specifically lacked the 4 A 2 → 4 T 1 ͑P͒ ligand-field feature of substitutional Co 2+ in ZnO, there was speculation that it should be attributed to phase-segregated precipitates. 10 Broad sub-band-gap ferromagnetic MCD features have also been observed in Mn:GaAs, 17 Cr:ZnTe, 18 and Mn:InAs, 19 however, materials for which the intrinsic origins of ferromagnetism are less controversial. We propose that the ferromagnetic MCD signal in Fig.…”

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confidence: 99%

Magnetic circular dichroism of ferromagnetic Co2+-doped ZnO

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Zhao

Liu

et al. 2006

Applied Physics Letters

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confidence: 99%

Magnetic circular dichroism of ferromagnetic Co2+-doped ZnO

Kittilstved

Zhao

Liu

et al. 2006

Applied Physics Letters

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“…For potential spintronic applications based on II-VI magnetic QDs, we anticipate that it is possible to further increase the magnetization and the temperature at which it vanishes. In addition to exploring a larger hole-Mn exchange coupling [22] in (II,Mn)VI QDs, it would also be advantageous to consider (II,Cr)VI QDs as there is a support for the room-temperature ferromagnetism in their bulk counterparts [27]. This work is supported by the US ONR, NSF-ECCS Career, the NRC HPC project, CIAR, and the CCR at SUNY Buffalo.…”

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confidence: 99%

Tailoring Magnetism in Quantum Dots

2007

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We study magnetism in magnetically doped quantum dots as a function of confining potential, particle numbers, temperature, and strength of Coulomb interactions. We explore possibility of tailoring magnetism by controlling the electron-electron Coulomb interaction, without changing the number of particles. The interplay of strong Coulomb interactions and quantum confinement leads to enhanced inhomogeneous magnetization which persist at higher temperatures than in the noninteracting case. The temperature of the onset of magnetization can be controlled by changing the number of particles as well as by modifying the quantum confinement and the strength of Coulomb interactions. We predict a series of electronic spin transitions which arise from the competition between the many-body gap and magnetic thermal fluctuations.PACS numbers: 75.75.+a,75.50.Pp, Magnetic doping of semiconductor quantum dots (QDs) provides an interesting interplay of interaction effects in confined geometries [1,2,3,4,5,6,7,8] and potential spintronic applications [9]. In the bulk-like dilute magnetic semiconductors the carrier-mediated ferromagnetism can be photoinduced [10,11] and electrically controlled by gate electrodes [12], suggesting possible nonvolatile devices with tunable optical, electrical, and magnetic properties [9]. QDs allow for a versatile control of the number of carriers, spin, and the effects of quantum confinement which could lead to improved optical, transport, and magnetic properties as compared to their bulk counterparts [1,13,14]. Unlike in the bulk structures, adding a single carrier in a magnetic QD can have important ramifications. An extra carrier can both strongly change the total carrier spin and the temperature of the onset of magnetization which we show can be further controlled by modifying the quantum confinement and the strength of Coulomb interactions.We study the magnetic ordering of carrier spin and magnetic impurities in (II,Mn)VI QDs identified as a versatile system to demonstrate interplay of quantum confinement and magnetism [4,5,6,15,16,17,18]. Because Mn is isoelectronic with group-II elements it does not change the number of carriers which in QDs are controlled by either chemical doping or by external electrostatic potential applied to the metallic gates. The latter allows confinement of the carriers in a dot with tunable size and shape [2]. By using real space finite-temperature local spin density approximation (LSDA) [19] we study temperature (T ) evolution of magnetic properties of QDs over a large parameter space. This approach allow us to consider QDs with varying number of interacting electrons (N ) and Mn impurities (N m ) which already for small N and N m becomes computationally inaccessible to the exact diagonalization techniques [18,20]. We extend the previous studies of Coulomb interactions in magnetic QDs with N m = 1, 2 at T = 0 [18] and T > 0 results using either Thomas-Fermi approximation or by applying Hund's rule with up to 6 carriers [17]. We reveal that the interplay of strong Cou...

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“…11 and 12͒ and even at room temperature with x = 0.20. 13,14 In addition, Pekarek et al found that the transition temperature is slightly above 300 K for the ferromagnetic phase in a bulk Zn 1−x Cr x Te crystal grown by vertical Bridgman method. 15 They ascribed the ferromagnetic signal to a pure CrTe minority phase.…”

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confidence: 99%

Chemical synthesis and magnetic properties of dilute magnetic ZnTe:Cr crystals

Zhao

Zhang

Pang

et al. 2006

Applied Physics Letters

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ZnTe and Cr doped ZnTe crystals have been synthesized using a solvothermal process. The characterizations by x-ray diffraction and transmission electron microscopy show that the synthesized ZnTe:Cr crystals have a cubic structure and Cr is incorporated into ZnTe. The magnetic properties of ZnTe:Cr are investigated. A hysteresis is observed in the magnetization versus magnetic field measurements below 10 K. The detailed analyses suggest that the hysteresis possibly originated from the magnetic short-range ordering of Zn 1−x Cr x Te compounds in the sample.

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Room-Temperature Ferromagnetism in a II-VI Diluted Magnetic SemiconductorZn1−xCrxT<

Cited by 415 publications

References 31 publications

Magnetic circular dichroism of ferromagnetic Co2+-doped ZnO

Magnetic circular dichroism of ferromagnetic Co2+-doped ZnO

Tailoring Magnetism in Quantum Dots

Chemical synthesis and magnetic properties of dilute magnetic ZnTe:Cr crystals

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