Horký Michal, Arregi Jon Ander, Patel Sheena K K, Staňo Michal, Medapalli Rajasekhar, Caha Ondřej, Vojáček Libor, Horák Michal, Uhlíř Vojtěch, Fullerton Eric E
CEITEC BUT, Brno University of Technology, Purkyňova 123, 612 00 Brno, Czechia.
Center for Memory and Recording Research, University of California San Diego, La Jolla, California 92093-0401, United States.
ACS Appl Mater Interfaces. 2022 Jan 19;14(2):3568-3579. doi: 10.1021/acsami.1c22460. Epub 2022 Jan 7.
Equiatomic and chemically ordered FeRh and MnRh compounds feature a first-order metamagnetic phase transition between antiferromagnetic and ferromagnetic order in the vicinity of room temperature, exhibiting interconnected structural, magnetic, and electronic order parameters. We show that these two alloys can be combined to form hybrid metamagnets in the form of sputter-deposited superlattices and alloys on single-crystalline MgO substrates. Despite being structurally different, the magnetic behavior of the alloys with substantial Mn content resembles that of the FeRh/MnRh superlattices in the ultrathin individual layer limit. For FeRh/MnRh superlattices, dissimilar lattice distortions of the constituent FeRh and MnRh layers at the antiferromagnetic-ferromagnetic transition cause double-step transitions during cooling, while the magnetization during the heating branch shows a smooth, continuous trend. For FeMnRh alloy films, the substitution of Mn at the Fe sites introduces an effective tensile in-plane strain and magnetic frustration in the highly ordered epitaxial films, largely influencing the phase transition temperature (by more than 150 K). In addition, Mn acts as a surfactant, enabling the growth of continuous thin films at higher temperatures. Thus, the introduction of hybrid FeRh-MnRh systems with adjustable parameters provides a pathway for the realization of tunable spintronic devices based on magnetic phase transitions.
等原子且化学有序的FeRh和MnRh化合物在室温附近呈现反铁磁和铁磁有序之间的一级亚磁相变，展现出相互关联的结构、磁性和电子有序参数。我们表明，这两种合金可以组合形成以溅射沉积在单晶MgO衬底上的超晶格和合金形式存在的混合亚磁体。尽管结构不同，但具有大量Mn含量的合金的磁行为在超薄单一层极限下类似于FeRh/MnRh超晶格的磁行为。对于FeRh/MnRh超晶格，在反铁磁-铁磁转变时，组成的FeRh和MnRh层的不同晶格畸变在冷却过程中导致双步转变，而加热分支期间的磁化呈现出平滑、连续的趋势。对于FeMnRh合金薄膜，Fe位点处的Mn替代在高度有序的外延薄膜中引入了有效的面内拉伸应变和磁阻挫，极大地影响了相变温度（超过150 K）。此外，Mn充当表面活性剂，使得能够在更高温度下生长连续薄膜。因此，引入具有可调参数的混合FeRh-MnRh系统为实现基于磁相变的可调自旋电子器件提供了一条途径。
