Moura K O, de Oliveira L A S, Rosa P F S, Jesus C B R, Saleta M E, Granado E, Béron F, Pagliuso P G, Pirota K R
Instituto de Física "Gleb Wataghin", Universidade Estadual de Campinas (UNICAMP), Campinas-SP, 13083-859, Brazil.
Núcleo Multidisciplinar de Pesquisa, Universidade Federal do Rio de Janeiro (UFRJ) - Campus Xerém, Duque de Caixias-RJ, 25245-390, Brazil.
Sci Rep. 2016 Jun 22;6:28364. doi: 10.1038/srep28364.
This work reports on the dimensionality effects on the magnetic behavior of Fe3Ga4 compounds by means of magnetic susceptibility, electrical resistivity, and specific heat measurements. Our results show that reducing the Fe3Ga4 dimensionality, via nanowire shape, intriguingly modifies its electronic structure. In particular, the bulk system exhibits two transitions, a ferromagnetic (FM) transition temperature at T1 = 50 K and an antiferromagnetic (AFM) one at T2 = 390 K. On the other hand, nanowires shift these transition temperatures, towards higher and lower temperature for T1 and T2, respectively. Moreover, the dimensionality reduction seems to also modify the microscopic nature of the T1 transition. Instead of a FM to AFM transition, as observed in the 3D system, a transition from FM to ferrimagnetic (FERRI) or to coexistence of FM and AFM phases is found for the nanowires. Our results allowed us to propose the magnetic field-temperature phase diagram for Fe3Ga4 in both bulk and nanostructured forms. The interesting microscopic tuning of the magnetic interactions induced by dimensionality in Fe3Ga4 opens a new route to optimize the use of such materials in nanostructured devices.
这项工作通过磁化率、电阻率和比热测量，报告了维度对Fe3Ga4化合物磁行为的影响。我们的结果表明，通过纳米线形状降低Fe3Ga4的维度，有趣地改变了其电子结构。特别是，块状体系表现出两个转变，一个铁磁（FM）转变温度T1 = 50 K，一个反铁磁（AFM）转变温度T2 = 390 K。另一方面，纳米线分别将这些转变温度向更高和更低温度移动，对于T1和T2而言。此外，维度降低似乎也改变了T1转变的微观性质。与在三维体系中观察到的从FM到AFM转变不同，对于纳米线发现的是从FM到亚铁磁（FERRI）转变或FM和AFM相共存。我们的结果使我们能够提出块状和纳米结构形式的Fe3Ga4的磁场 - 温度相图。Fe3Ga4中维度诱导的磁相互作用的有趣微观调控为在纳米结构器件中优化此类材料的使用开辟了一条新途径。
