Optical properties and electronic structure of yttrium oxysulfide

Itoh, Minoru; Inabe, Yoshiyuki

doi:10.1103/physrevb.68.035107

Cited by 31 publications

(32 citation statements)

References 15 publications

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“…The bandgap separating the valence and the conduction bands is 2.94 eV, somewhat smaller than that in La 2 O 2 S, but significantly smaller than that found for A-La 2 O 3 . This result is in qualitative agreement with experimental data, except for the anomalously high value of 6.77 eV reported in reference [58].…”

Section: Y 2 O 2 Ssupporting

confidence: 93%

“…Except for the cases of La 2 TeO 6 and Y 2 TeO 6 , the electronic structure of the compounds included in this work has been studied previously using different computational approaches [45][46][47][48][49][52][53][54][55][56][57][58][59][60]. Since one of our principal aims is to obtain a general picture of the nature of the valence and conduction bands for all these compounds and its influence on the resulting optical properties, we will center our discussion on the density of states in the energy region around the band gap.…”

Section: Electronic Structurementioning

confidence: 99%

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Electronic, structural, and optical properties of host materials for inorganic phosphors

Alemany¹,

Moreira²,

Castillo³

et al. 2012

Journal of Alloys and Compounds

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Section: Y 2 O 2 Ssupporting

confidence: 93%

Section: Electronic Structurementioning

confidence: 99%

Electronic, structural, and optical properties of host materials for inorganic phosphors

Alemany¹,

Moreira²,

Castillo³

et al. 2012

Journal of Alloys and Compounds

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“…The local electronic structures, viz., the energy levels of the atomic orbitals and the density of states (DOS) of Ce 3+ -doped Sr3AlO4F, were calculated by using the relativistic DV-X␣ method based on first-principles molecular orbitals (MO) approach [23][24][25][26]. On the basis of the crystal structure of Sr3AlO4F [20,21], the cluster models of [Ce(I)O8F2] −15 and [Ce(II)O6F2] −11 were built up for Ce 3+ -doped Sr3AlO4F corresponding to the point groups of D4 and Cs symmetry, respectively, in which the Ce 3+ ions are assumed to be randomly substituted for the two Sr ions.…”

Section: Computational Proceduresmentioning

confidence: 99%

Photoluminescence properties and local electronic structures of rare earth-activated Sr3AlO4F

Fang

Qiu

et al. 2010

Journal of Alloys and Compounds

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“…, and t R L t I t R L ;I t 0:4 eV, where the Fermi energy E F 0 eV, and the t L;I and t R;I are the NN hopping matrix elements at the two FM=I interfaces [14]. Note that L R , refers to the local effective s-d exchange interaction, with values between 0.2 eV to 2 eV [15] depending on the material.…”

mentioning

confidence: 99%

Anomalous Bias Dependence of Spin Torque in Magnetic Tunnel Junctions

et al. 2006

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We predict an anomalous bias dependence of the spin transfer torque parallel to the interface, T k , in magnetic tunnel junctions, which can be selectively tuned by the exchange splitting. It may exhibit a sign reversal without a corresponding sign reversal of the bias or even a quadratic bias dependence. We demonstrate that the underlying mechanism is the interplay of spin currents for the ferromagnetic (antiferromagnetic) configurations, which vary linearly (quadratically) with bias, respectively, due to the symmetric (asymmetric) nature of the barrier. The spin transfer torque perpendicular to interface exhibits a quadratic bias dependence. DOI: 10.1103/PhysRevLett.97.237205 PACS numbers: 85.75.ÿd, 72.10.ÿd, 72.25.ÿb, 73.40.Gk Theoretical calculations predict that when a spinpolarized current passes through a magnetic multilayer structure, whether spin valve [1] or magnetic tunnel junction, (MTJ) [2,3], it can transfer spin angular momentum from one ferromagnetic electrode to another, and hence exert a torque on the magnetic moments of the electrodes. At sufficiently high current densities, this spin transfer can stimulate spin-wave excitations [4,5] and even reverse the magnetization of an individual domain [6]. Currentinduced magnetic switching (CIMS) has now been confirmed in numerous experiments both in spin valves [6,7] and more recently, in MTJs [8,9]. Thus, CIMS provides a powerful new tool for the study of spin transport in magnetic nanostructures. In addition, it offers the intriguing possibility of manipulating high-density nonvolatile magnetic-device elements, such as magnetoresistive random access memory (MRAM), without applying cumbersome magnetic fields [10].While the fundamental physics underlying the spin transfer torque (STT) in spin valves has been extensively studied theoretically [1,[11][12][13], its role in MTJs remains an unexplored area thus far, except for the pioneering work of Slonczewski [2,3], who employed the free-electron model in the low bias regime. One of the most pressing needs is a comprehensive understanding of the bias dependence of the STT in MTJs, which will be important for the development of MRAM that uses CIMS for writing the magnetic memory cell.In this Letter, we present for the first time a comprehensive study of the effect of bias on the spin torques, parallel (T k ) and perpendicular (T ? ) to the interface, in MTJs, using tight-binding (TB) calculations and the nonequilibrium Keldysh formalism. We predict an anomalous bias dependence of the spin torque, contrary to the general consensus. We demonstrate first that depending on the exchange splitting, T k may exhibit an unusual nonmonotonic bias dependence: it may change sign without a sign reversal in bias or current, and it may even have a quadratic bias dependence. Second, by generalizing the equivalent circuit in Ref.[3] using angular-dependent resistances, we show that T k satisfies an expression involving the difference in spin currents between the ferromagnetic (FM) and antiferromagnetic (AF) configurat...

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Optical properties and electronic structure of yttrium oxysulfide

Cited by 31 publications

References 15 publications

Electronic, structural, and optical properties of host materials for inorganic phosphors

Electronic, structural, and optical properties of host materials for inorganic phosphors

Photoluminescence properties and local electronic structures of rare earth-activated Sr3AlO4F

Anomalous Bias Dependence of Spin Torque in Magnetic Tunnel Junctions

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