High-Field EPR of Zn_1-xCr_xTe

Abstract

High magnetic field electron paramagnetic resonance experiments have been performed on Ζn1-xCrxTe covering the energy range 1-7 cm -1 in fields up to 20 T at T = 1.2 K. The static magnetic field was oriented along the (100), (110) and (111) crystallographic axes of the sample. Pronounced absorptioii lines for intra-chromium transitions have been observed for these different orientations, revealing a strong anisotropy due to a static Jahn-Teller distortion. The measured low energy level structure of the C r ++ ion can be described by a cubic crystal field model including this distortion of the Cr centers.PACS numbers: 75.50. Ppa, 76.30.Fc, 78.30.Fs Diluted magnetic semiconduction (DMS) or semimagnetic semiconduction (SMSC) are semiconductors (mostly II-VI) where a controlled fraction of the cations is randomly substituted by magnetic ions [1]. On the contrary to the well-known Mn, Fe and Co based DMS, the Cr based DMS are the first SMSC known so far with a ferromagnetic p-d exchange between the two coexisting electronic subsystems, the localized d-electrons of the Cr++ ion and the ZnTe band electrons [2]. From the magnetic point of view the Cr-SMSC have an intermediate character between that of a Brillouin-type paramagnet and a Van Vleck-type system. Moreover the Cr++ center in a tetrahedral crystal field undergoes a static Jahn-Teller distortion along one of the (100) axes of the crystal, which results in the existence of three types of nonequivalent Cr++ centers. This leads to pronounced anisotropy of the Cr++ ion energy level stucture and magnetic properties [3].To understand the low temperature magnetic properties of Zn1-x Crx Te, we need to know the exact low energy level stucture of the Cr++ ion. This energy diagram consists of five closely lying energy levels in the energy range between 0 and 8 cm -1 (ΔΕ N kBT, T = 4.2 K), with a complicated magnetic field dependence. A standard EPR setup typically operates at one fixed frequency between (829)

Magnetization and exciton spectroscopy of the diluted magnetic semiconductorCd1−xCrxSHerbich1, Mac2, Twardowski3 et al. 1998Phys. Rev. BSelf Cite402171View full textAdd to dashboardCite

“…26,34 The hexagonal crystal field along the c axis lifts the degeneracy of ⌫ 5 ͑doublet becomes a semidoublet͒. Finally external magnetic field, described by the Zeeman term H B ϭ B (L ϩ2Ŝ )B, lifts all of the remaining degeneracies.…”