Thes-dandp-dexchange interaction inZn1−xFe

Abstract

The exciton splitting induced by the s-d and p-d exchange interaction in Zn 1Ϫx Fe x Te (xϽ0.005) was studied by polarized magnetoreflectance. Data were taken at 2 K in magnetic fields up to 5 T. Combining these results with magnetization data, a value (N 0 ␣ϪN 0 ␤) ϭ 2.1Ϯ0.4 eV was obtained for the difference between the s-d and p-d exchange constants. Assuming that N 0 ␣ϭϩ0.2 eV, the p-d exchange is antiferromagnetic, with a magnitude N 0 ␤ϭϪ1.9 eV.

Quantum Phase Transition from Superparamagnetic to Quantum Superparamagnetic State in Ultrasmall Cd1–xCr(II)xSe Quantum Dots?

“…Cr(II) has a non-vanishing orbital momentum resulting in intermediate behavior between van Vleck and Brillouin paramagnetism, as well as a mutliplet ground state ( 5 T 2g , JT distorted 5 B 2g ground state). 34 The electronic energy structure of Cr(II) simultaneously with the JT effect has been reported in quite a few papers. 58,59 SpinÀorbit (SO) coupling results in further splitting, producing for Se and S lattices two unresolved singlet ground states (Γ 1 and Γ 2 ), a singlet excited state (Γ 4 ), and a doublet excited state (Γ 5 ) (Supporting Information S2).…”

“…69 Magnetic circular dichroism (MCD) experiments on Cr(II)-doped IIÀVI semiconductors have confirmed the presence of strong pÀd exchange leading to ferromagnetic DMS behavior. 34 Recently, MCD in Zn 1Àx Cr x Te films (with x = 0.2) revealed the occurrence of room-temperature (300 K) FM. 74,75 Saito et al demonstrated that Zn 1Àx Cr x Te is the third real ferromagnetic DMS after In 1Àx Mn x As and Ga 1Àx Mn x As, in which the spÀd exchange interaction could be used to develop spintronic devices.…”

“…29À33 The most prominent difference between Cr(II)-based DMS materials is the presence of a half-metallic state due to the spin-up and spin-down levels in Cr(II) existing at the Fermi level, which leads to efficient ferromagnetic pÀd exchange (β) between the Se (4p) valence-band electrons and the 3d-levels for the Cr(II) ions. 34 The formation of a ferromagnetic DMSQD from Cr(II) doping leads to speculation of the potential for a quantum critical point due to long-range ordering (LRO) at low temperature. Quantum tunneling behavior that transfers from the blocked superparamagnetic (SP) state to the quantum-superparamagnetic (QSP) state was suggested in CoFe 2 O 4 nanoparticles.…”

High Curie Temperature and Half‐Metallic Ferromagnetism in ZnSe:Co,Ni with Wurtzite Structure: First‐Principles Study

“…[23] In refs. [24][25][26][27][28][29][30][31][32], it was reported that Cr impurities in II-VI semiconductors make FM materials at room temperature.Zinc selenide, a semiconductor, can operate as a half-metallic compound and is a helpful material for optoelectronic and spintronic applications. Zinc selenide is a nonmagnetic material with a direct bandgap of 2.70 eV and has great potential for a diversity of optical and electro-optical devices, such as short wavelength lasers, blue-green laser diodes, pure green lightemitting diodes, microwave and terahertz devices, solar cells and tunable mid-IR laser sources.…”

“…[23] In refs. [24][25][26][27][28][29][30][31][32], it was reported that Cr impurities in II-VI semiconductors make FM materials at room temperature.…”