Spin-valve-like magnetoresistance in Mn2NiGa at room temperature.
Spin-valve-like magnetoresistance in Mn2NiGa at room temperature.
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DOI：
10.1103/physrevlett.109.246601
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发表时间：
2012-12
影响因子：
8.6
通讯作者：
Sanjay Singh;R. Rawat;S. E. Muthu;S. W. D'Souza;E. Suard;A. Senyshyn;S. Banik;P. Rajput;S. Bh
中科院分区：
文献类型：
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作者：
Sanjay Singh;R. Rawat;S. E. Muthu;S. W. D'Souza;E. Suard;A. Senyshyn;S. Banik;P. Rajput;S. Bh
自旋阀已经彻底改变了磁记录和存储设备领域。自旋阀一般是在薄膜异质结构中实现的，其中两个铁磁层被一个非磁性导电层隔开。在这里，我们展示了室温下具有自旋阀样磁电阻的块状铁磁材料，该材料具有磁形状记忆效应。通过中子衍射、磁化和从头算理论计算，研究了Mn(2)NiGa中这种意外行为的起源。中子衍射图的细化表明存在反位紊乱，其中约13%的Ga位被Mn原子占据。根据中子衍射和理论计算得到的磁性结构，我们确定了这些反位缺陷导致Mn自旋矩平行排列的FM纳米团簇在具有反平行Mn自旋矩的Mn(2)NiGa体晶格中形成。软调频簇中Mn矩的方向与外磁场相反。这导致团簇-晶格界面上反平行Mn矩的旋转或倾斜，从而导致所观察到的磁电阻不对称。
Spin valves have revolutionized the field of magnetic recording and memory devices. Spin valves are generally realized in thin film heterostructures, where two ferromagnetic (FM) layers are separated by a nonmagnetic conducting layer. Here, we demonstrate spin-valve-like magnetoresistance at room temperature in a bulk ferrimagnetic material that exhibits a magnetic shape memory effect. The origin of this unexpected behavior in Mn(2)NiGa has been investigated by neutron diffraction, magnetization, and ab initio theoretical calculations. The refinement of the neutron diffraction pattern shows the presence of antisite disorder where about 13% of the Ga sites are occupied by Mn atoms. On the basis of the magnetic structure obtained from neutron diffraction and theoretical calculations, we establish that these antisite defects cause the formation of FM nanoclusters with parallel alignment of Mn spin moments in a Mn(2)NiGa bulk lattice that has antiparallel Mn spin moments. The direction of the Mn moments in the soft FM cluster reverses with the external magnetic field. This causes a rotation or tilt in the antiparallel Mn moments at the cluster-lattice interface resulting in the observed asymmetry in magnetoresistance.