Ramírez Camacho M C, Sánchez Valdés C F, Curiel M, Sánchez Llamazares J L, Siqueiros J M, Raymond Herrera O
Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de México, AP 14, 22860, Ensenada, Baja California, México.
Instituto de Ingeniería, Universidad Autónoma de Baja California, Mexicali, Blvd. Benito Juarez s/n, 21280, Baja California, México.
Sci Rep. 2020 Feb 13;10(1):2568. doi: 10.1038/s41598-020-59334-3.
A novel superparamagnetic state has been observed in high quality LaSrMnO (LSMO) thin films directly grown by rf-sputtering on SiO/Si(100) substrates. The films are nanostructured without grain boundaries, constituted by locally epitaxial nanoregions grown layer-by-layer with out-of-plane (012) preferential orientation, induced by the constrain of the native silicon oxide. Low magnetic field ZFC-FC magnetization curves show a cross-over from superparamagnetic to ferromagnetic state dependent of the thickness. The thicker film (140 nm) exhibits typical ferromagnetic order. The thinner films (40 and 60 nm) exhibit superparamagnetic behavior attributed to interacting ferromagnetic monodomain nanoregions with critical size, random in-plane oriented, where the inter-monodomain boundaries with surface spin-glass structure regulate the blocking of magnetization depending on the magnetic field intensity. M(H) hysteresis loops showed noticeable coercive fields in all samples, larger than those reported for LSMO. Such properties of half-metal LSMO film foresee potential integration in new Si-technology nanodevices in Spintronics.
在通过射频溅射直接生长在SiO/Si(100)衬底上的高质量LaSrMnO（LSMO）薄膜中观察到了一种新型的超顺磁状态。这些薄膜是无晶界的纳米结构，由在原生氧化硅的约束下逐层生长的具有面外（012）择优取向的局部外延纳米区域构成。低磁场ZFC-FC磁化曲线显示出从超顺磁到铁磁状态的转变，这取决于薄膜的厚度。较厚的薄膜（140纳米）表现出典型的铁磁序。较薄的薄膜（40和60纳米）表现出超顺磁行为，这归因于具有临界尺寸、面内随机取向的相互作用的铁磁单畴纳米区域，其中具有表面自旋玻璃结构的单畴间边界根据磁场强度调节磁化的阻塞。M(H)磁滞回线在所有样品中都显示出明显的矫顽场，比报道的LSMO的矫顽场更大。半金属LSMO薄膜的这些特性预示着在自旋电子学中的新型硅技术纳米器件中具有潜在的集成可能性。
