Nayak Sagarika, Manna Palash Kumar, Singh Braj Bhusan, Bedanta Subhankar
Laboratory for Nanomagnetism and Magnetic Materials (LNMM), School of Physical Sciences, National Institute of Science Education and Research (NISER), HBNI, P.O.- Bhimpur Padanpur, Via-Jatni, 752050, India.
Phys Chem Chem Phys. 2021 Mar 21;23(11):6481-6489. doi: 10.1039/d0cp05726f. Epub 2021 Mar 12.
Exchange bias in ferromagnetic/antiferromagnetic systems can be explained in terms of various interfacial phenomena. Among these, spin glass frustration can affect the magnetic properties in exchange bias systems. Here we have studied a NiMn/CoFeB exchange bias system in which spin glass frustration seems to play a crucial role. In order to account for the effect of spin glass frustration on magnetic properties, we have investigated the temperature and cooling field dependence of exchange bias. We have observed the decrease of exchange bias field (μH) with cooling field (μH) whereas there is a negligible effect on coercive field (μH). Exponential decay of μH and μH is found in this exchange bias system. Furthermore, training effect measurements have been performed to study the spin relaxation mechanism. We have fitted the training effect data with a frozen and rotatable spin relaxation model. We have determined the ratio of relaxation rates of interfacial rotatable and frozen spins in this study. The training effect data are also fitted with various other models. Furthermore, we have observed the shifting of the peak temperature towards higher temperature with frequency from the ac susceptibility data. The peak temperature vs. frequency data can be described by the Vogel-Fulcher law, which indicates the spin glass like state in the bilayer system.
铁磁/反铁磁系统中的交换偏置可以用各种界面现象来解释。其中，自旋玻璃失配会影响交换偏置系统的磁性能。在此，我们研究了一个NiMn/CoFeB交换偏置系统，其中自旋玻璃失配似乎起着关键作用。为了说明自旋玻璃失配对磁性能的影响，我们研究了交换偏置的温度和冷却场依赖性。我们观察到交换偏置场（μH）随冷却场（μH）减小，而对矫顽场（μH）的影响可忽略不计。在这个交换偏置系统中发现了μH和μH的指数衰减。此外，还进行了训练效应测量以研究自旋弛豫机制。我们用一个冻结且可旋转的自旋弛豫模型拟合了训练效应数据。在本研究中，我们确定了界面可旋转和冻结自旋的弛豫率之比。训练效应数据也用各种其他模型进行了拟合。此外，从交流磁化率数据中我们观察到峰值温度随频率向更高温度移动。峰值温度与频率的数据可以用Vogel-Fulcher定律来描述，这表明双层系统中存在类似自旋玻璃的状态。
