Department of Physics, Zhejiang University, Hangzhou 310027, People's Republic of China.
J Phys Condens Matter. 2014 Jan 15;26(2):026002. doi: 10.1088/0953-8984/26/2/026002. Epub 2013 Dec 9.
Ba0.6K0.4Fe2Se3 (BKFS) single crystals were investigated by means of measurements of powder x-ray diffraction, temperature-dependent resistivity, anisotropic dc magnetization, ac magnetic susceptibility and specific heat. The powder x-ray diffraction indicates staggered iron displacements along the ladders with short and long Fe-Fe bond lengths (2.64(2) and 2.91(2) Å) variation. The resistivity of BKFS exhibits variable range hopping behavior with ln(ρ) ~ T(-1/2) at low temperature. The magnetic susceptibility χ(T) exhibits a sharp cusp at around 20 K in a zero-field-cooled process. The frequency-dependent ac magnetic susceptibility reveals that the cusp feature is attributable to spin glass behavior. The anisotropic ac magnetic susceptibility indicates that BKFS is probably an anisotropic Heisenberg-like spin glass with its easy magnetization plane perpendicular to the chain direction. The specific heat also supports an insulating and spin glass ground state. Extended Curie-Weiss behavior above 40 K was observed with a reduced effective moment (μ(eff) = 1.66 μ(B)/Fe for H is perpendicular to b and μ(eff) = 1.82 μB/Fe for H is parallel to b) in BKFS, which is close to the spin-only magnetism with S=1/2.
钡铁硒 0.6 钾 0.4（BKFS）单晶通过粉末 X 射线衍射、温度相关电阻率、各向异性直流磁化率、交流磁化率和比热的测量进行了研究。粉末 X 射线衍射表明，铁沿梯子的交错位移具有短和长 Fe-Fe 键长（2.64(2) 和 2.91(2) Å）的变化。BKFS 的电阻率在低温下表现出变程跳跃行为，ln(ρ)~T(-1/2)。零场冷却过程中，磁化率 χ(T)在 20 K 左右出现尖锐的拐点。频率相关的交流磁化率表明，拐点特征归因于自旋玻璃行为。各向异性交流磁化率表明，BKFS 可能是各向异性的海森堡型自旋玻璃，其易磁化平面垂直于链方向。比热也支持绝缘和自旋玻璃基态。在 40 K 以上观察到扩展的居里-外斯行为，有效磁矩减小（对于 H 垂直于 b，μ(eff)=1.66 μ(B)/Fe，对于 H 平行于 b，μ(eff)=1.82 μB/Fe），这接近于自旋为 1/2 的自旋单磁体。
