ic8b02384_si_001.pdf (650.91 kB)
Cr2.37Ga3Se8: A Quasi-Two-Dimensional Magnetic Semiconductor
journal contribution
posted on 2018-10-20, 00:48 authored by Yazhou Zhou, Lingyi Xing, Gregory J. Finkelstein, Xin Gui, Madalynn G. Marshall, Przemyslaw Dera, Rongying Jin, Weiwei XieWe present a novel magnetic semiconductor,
Cr2.37Ga3Se8, synthesized by partially
replacing magnetic Cr3+ in antiferromagnetic Cr5+δSe8 with nonmagnetic Ga3+. The crystal structure
of Cr2.37Ga3Se8 was determined by
both powder and single-crystal X-ray diffraction. The title compound
crystallizes in a monoclinic structure with space group C2/m (No. 12). In Cr2.37Ga3Se8, the Cr atoms are surrounded by 6 Se atoms and form
filled octahedral clusters, while Ga atoms are centered in the Se4 tetrahedral clusters. The two kinds of clusters pack alternatingly
along the c-axis, which results in a quasi-two-dimensional
layered structure. The magnetization (M) measurement
shows the development of short-range ferromagnetic coupling below
the Curie–Weiss (CW) temperature θCW ∼
92 K, evidenced by the nonlinear field dependence of M. However, the magnetic susceptibility exhibits a peak at low fields
at ∼18 K, indicating the existence of an antiferromagnetic
interaction as well. Electronic structure calculations using the WIEN2k
program in the local spin density approximation indicate that the
magnetism arises exclusively from local moments of the Cr atoms. The
electrical resistivity measurement of the Cr2.37Ga3Se8 sample confirms that this material is a semiconductor
with the band gap ∼0.26 eV. Meanwhile, the experimental band
gap (∼0.26 eV) is close to the theoretical prediction using
the WIEN2k program (∼0.35 eV).