De Pietro L, Bertolini G, Peter Q, Cabrera H, Vindigni A, Gürlü O, Pescia D, Ramsperger U
Laboratorium fur Festkörperphysik, ETH Zürich, Zürich, 8093, Switzerland.
Department of Physics, Istanbul Technical University, Maslak, 34469, Istanbul, Turkey.
Sci Rep. 2017 Oct 16;7(1):13237. doi: 10.1038/s41598-017-13453-6.
The current flowing through a Mott spin junction depends on the relative spin orientation of the two ferromagnetic layers comprising the "source" and "drain" sides of the junction. The resulting current asymmetry is detected as giant or tunnelling magnetoresistance depending on whether the two ferromagnets are separated by a metal or an insulator. Based on the fundamental principles of reciprocity for spin-dependent electron scattering, one can envisage a one-magnet-only spin junction in which the source is non-magnetic, and the spin information is encoded by the spin polarisation of the electrons that have crossed or are backscattered from the drain magnetic layer. The practical significance of using an unpolarised source is that the state of the magnetic layer can be modified without affecting the process of probing it. Whether this reciprocity is realised in the actual junctions is not yet known. Here, we demonstrate a nano-sized, one-magnet-only Mott spin junction by measuring the finite spin polarisation of the backscattered electrons. Based on this finding, we conclude that since the junction acts as a spin filter, the magnetic layer must experience a spin transfer that could become detectable in view of the high current densities achievable in this technology.
流经莫特自旋结的电流取决于构成该结“源”和“漏”两侧的两个铁磁层的相对自旋取向。根据两个铁磁体是被金属还是绝缘体隔开，所产生的电流不对称性被检测为巨磁电阻或隧穿磁电阻。基于自旋相关电子散射的互易性基本原理，可以设想一种仅含一个磁体的自旋结，其中源是非磁性的，自旋信息由穿过漏磁层或从漏磁层背散射的电子的自旋极化编码。使用非极化源的实际意义在于，可以在不影响探测磁层过程的情况下改变磁层的状态。在实际结中是否实现了这种互易性尚不清楚。在此，我们通过测量背散射电子的有限自旋极化，展示了一种纳米尺寸、仅含一个磁体的莫特自旋结。基于这一发现，我们得出结论，由于该结起到自旋滤波器的作用，鉴于此技术可实现的高电流密度，磁层必定经历了自旋转移，而这种自旋转移可能变得可检测。
