Increasing the Néel temperature of magnetoelectric chromia for voltage-controlled spintronics

Street, Mike; Echtenkamp, Will; Komesu, Takashi; Cao, Shi; Dowben, Peter A.; Binek, Christian

doi:10.1063/1.4880938

Cited by 75 publications

(65 citation statements)

References 28 publications

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“…15 They reported that 1% substitution of boron at the oxygen sites can enhance T N by 10%, without destroying the AFM ordering in Cr 2 O 3 . Experimentally, Street et al 16 confirmed the enhancement of T N in chromia thin films fabricated by pulsed laser deposition from a Cr 2 O 3 target in a decaborane (B 10 H 14 ) gas environment. However, doping at anion sites will be difficult because B prefers the trivalent B 3þ state.…”

Section: Introductionmentioning

confidence: 90%

Néel temperature of Cr2O3 in Cr2O3/Co exchange-coupled system: Effect of buffer layer

Pati

Shimomura

Nozaki

et al. 2015

Journal of Applied Physics

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The lattice parameter dependence of the N eel temperature T N of thin Cr 2 O 3 in a Cr 2 O 3 /Co exchange-coupled system is investigated. Lattice-mismatch-induced strain is generated in Cr 2 O 3 by using different buffer layers. The lattice parameters are determined from out-of-plane and in-plane X-ray diffraction measurements. The N eel temperature is detected by direct temperature-dependent magnetization measurement as well as the temperature-dependent interface exchange coupling energy. It is observed that in-plane lattice contraction can enhance T N in Cr 2 O 3 , which is consistent with theoretical calculations. V C 2015 AIP Publishing LLC. [http://dx.

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Section: Introductionmentioning

confidence: 90%

Néel temperature of Cr2O3 in Cr2O3/Co exchange-coupled system: Effect of buffer layer

Pati

Shimomura

Nozaki

et al. 2015

Journal of Applied Physics

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“…In order to suppress these noise sources, it was necessary to measure the magnetic signal in the complete absence of any applied magnetic field, a condition that was achieved by quenching [28] the superconducting magnet of our magnetometer prior to every measurement sequence. Correspondingly, we have utilized a rather specific T and H dependent measurement protocol, consisting of a zero field heating (ZFH) magnetization measurement sequence, starting at T = 100 K and followed up to T = 350 K, after first high-field cooling (FC) the sample from T = 350 K down to T = 100 K. Details of this measurement procedure have been published elsewhere [12,13,29]. Fig.7 shows the resulting temperature dependence of the out-ofplane remnant magnetic moment m for the entire set of our epitaxial Cr (2-x) Al (x) O 3 alloy films after prior FC in an applied magnetic field of μ 0 H = 7 T. All data show a positive magnetization value at low temperature due to the positive magnetic field applied during FC, which leads to the selection of a state with positive BM.…”

Section: B Magnetic Characterizationmentioning

confidence: 99%

Boundary magnetization properties of epitaxialCr2−xAlxO3thin fi

2015

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The magnetoelectric antiferromagnet α-Cr 2 O 3 (Chromia) is known to possess a roughness insensitive net equilibrium magnetization at the (0001) surface, called boundary magnetization (BM), which is coupled to the bulk antiferromagnetic order parameter. In order to verify whether this symmetry sensitive BM persists in alloys, we investigate the impact of diamagnetic dilution on Chromia thin films alloyed with the isostructural α-Al 2 O 3 (Alumina). Single crystalline Cr (2-x) Al (x) O 3 thin films with (0001) surface orientation and varying stoichiometry have been grown by sputter co-deposition in the concentration range between x = 0 and x = 0.6 . For these samples, we find the corundum crystal structure, the antiferromagnetic ordering and the boundary magnetization to be preserved. We also find that the critical temperature T N can be tuned by alloying with α-Al 2 O 3, using the BM as a probe to study the magnetic phase transition. Furthermore, we were able to evaluate the critical exponent and the absolute BM values for different samples. Both properties corroborate that the observed magnetic signals originate from the BM rather than the bulk of the samples.2

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“…For such a spin FET to actually work, based on the induced polarization from the gate, the device requires a dielectric gate with interface polarization in proximity to the graphene. Most promising would be a nonvolatile spin-FET, with a multiferroic or magnetoelectric gate dielectric, having high interface polarization like chromia , where the interface polarization can be controlled by voltage , He 2010, Street 2014. There have already been several efforts to investigate the induced magnetism or spin polarization in graphene supported on magnetic insulators.…”

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confidence: 99%