Inverse-Heusler合金Ti_(2)NiAl/MgO(100)异质结的结构、磁性以及电子性质

Structure,magnetism,and electronic properties of inverse Heusler alloy Ti_(2)NiAl/MgO(100) herterojuction

本文通过第一原理计算,研究了Ti_(2)NiAl/MgO(100)异质结Ti Al-O、TiNi-Mg、TiNi-O和Ti AlMg这4种原子端面的界面结构、原子磁性、态密度和自旋极化.在平衡界面结构中,由于原子间相互作用力的存在,Ti-Mg (Ni-Mg)键的长度远大于Ti-O (Ni-O)键的长度.在所有端面中,原来块体出现的半金属间隙都遭受了界面态的不同程度破坏.在Ti_(2)Ni Al/MgO(100)异质结中,TiNi-O界面检测到具有最大76%左右自旋极化率,根据Julliere模型预测Ti_(2)NiAl/MgO(100)异质结在低温下的隧道磁电阻值(TMR)可以达到281%.

The interface structures,atomic magnetism,density of states,and spin polarization of TiAl-O,TiNi-Mg,TiNi-O,and TiAl-Mg atomic terminations in the Ti_(2)NiAl/MgO(100) heterojunction are investigated by the first-principles calculation. In the equilibrium interface structures,the length of Ti-Mg(Ni-Mg)bond is much longer than that of Ti-O(Ni-O) bond due to the interaction between atoms. In all terminations,he half-metallic gap in the bulk phase is destroyed by the surface states. In the TiNi-O termination,the maximum spin polarizability is about 76%. According to the Julliere model,the tunnel magnetoresistance value of about 281% in the Ti_(2)NiAl/MgO(100) heterojunction at low temperature is predicted.