Gandhi Ashish Chhaganlal, Selvam Rajakar, Cheng Chia-Liang, Wu Sheng Yun
Department of Physics, National Dong Hwa University, Hualien 97401, Taiwan.
Nanomaterials (Basel). 2021 Mar 7;11(3):648. doi: 10.3390/nano11030648.
We report a room temperature magnetic memory effect (RT-MME) from magnetic nanodiamond (MND) (ND)/γ-FeO nanocomposites. The detailed crystal structural analysis of the diluted MND was performed by synchrotron radiation X-ray diffraction, revealing the composite nature of MND having 99 and 1% weight fraction ND and γ-FeO phases, respectively. The magnetic measurements carried out using a DC SQUID magnetometer show the non-interacting superparamagnetic nature of γ-FeO nanoparticles in MND have a wide distribution in the blocking temperature. Using different temperature, field, and time relaxation protocols, the memory phenomenon in the DC magnetization has been observed at room temperature (RT). These findings suggest that the dynamics of MND are governed by a wide distribution of particle relaxation times, which arise from the distribution of γ-FeO nanoparticle size. The observed RT ferromagnetism coupled with MME in MND will find potential applications in ND-based spintronics.
我们报道了磁性纳米金刚石（MND）（ND）/γ-FeO纳米复合材料的室温磁记忆效应（RT-MME）。通过同步辐射X射线衍射对稀释后的MND进行了详细的晶体结构分析，揭示了MND的复合性质，其分别具有99%和1%重量分数的ND相和γ-FeO相。使用直流超导量子干涉仪磁力计进行的磁性测量表明，MND中γ-FeO纳米颗粒的非相互作用超顺磁性质在阻塞温度方面具有广泛分布。使用不同的温度、磁场和时间弛豫方案，在室温（RT）下观察到了直流磁化中的记忆现象。这些发现表明，MND的动力学受粒子弛豫时间的广泛分布支配，这源于γ-FeO纳米颗粒尺寸的分布。在MND中观察到的室温铁磁性与MME相结合，将在基于ND的自旋电子学中找到潜在应用。
