Effect of thermal deformation on giant magnetoresistance of flexible spin valves grown on polyvinylidene fluoride membranes

• Published in: Chinese physics B Vol. 25; no. 7; pp. 407 - 411
• Main Author: 刘鲁萍 詹清峰 荣欣 杨华礼 谢亚丽 谭晓华 李润伟
• Format: Journal Article
• Language: English
• Published: 01.07.2016
• Subjects: PVDF; 单轴各向异性; 巨磁电阻效应; 温度降低; 热变形; 聚偏氟乙烯; 膜生长; 自旋阀
• ISSN: 1674-1056; 2058-3834
• DOI: 10.1088/1674-1056/25/7/077307

We fabricated flexible spin valves on polyvinylidene fluoride（PVDF） membranes and investigated the influence of thermal deformation of substrates on the giant magnetoresistance（GMR） behaviors. The large magnetostrictive Fe_（81）Ga_（19）（Fe Ga） alloy and the low magnetostrictive Fe_（19）Ni_（81）（Fe Ni） alloy were selected as the free and pinned ferromagnetic layers.In addition, the exchange bias（EB） of the pinned layer was set along the different thermal deformation axes α_（31） or α_（32） of PVDF. The GMR ratio of the reference spin valves grown on Si intrinsically increases with lowering temperature due to an enhancement of spontaneous magnetization. For flexible spin valves, when decreasing temperature, the anisotropic thermal deformation of PVDF produces a uniaxial anisotropy along the α_（32） direction, which changes the distribution of magnetic domains. As a result, the GMR ratio at low temperature for spin valves with EB α_（32）becomes close to that on Si, but for spin valves with EB α_（31）is far away from that on Si. This thermal effect on GMR behaviors is more significant when using magnetostrictive Fe Ga as the free layer.