Morin transition temperature in (0001)-oriented α-Fe2O3 thin film and effect of Ir doping

Abstract

The structural properties and Morin transition in c-plane-oriented α-Fe2O3 and Ir-doped α-Fe2O3 thin films have been investigated. The enhancement of the Morin transition temperature (TM) in α-Fe2O3 film by Ir doping has been demonstrated. The TM in the c-plane-oriented α-Fe2O3 thin film was determined from the temperature-dependent in-plane magnetization and change of coercivity (Hc); this TM value was found close to that of bulk α-Fe2O3. The spin directions of non-doped and Ir-doped α-Fe2O3 at room temperature were also estimated from conversion electron Mössbauer spectroscopy measurements. We confirmed that Ir doping dramatically enhances the TM of α-Fe2O3 thin film.

Quantitative Study on Current-Induced Effect in an Antiferromagnet Insulator/Pt Bilayer Film

“…The magnetization hysteresis curves measured with a SQUID magnetometer at 300 K are illustrated in Fig. 1c, which show a small Ms around 1.5~2 emu/cc and a coercive field of 500~1000 Oe within the entire thickness range (10~120 nm), consistent with the reported values in previous literatures 18,19 . In order to study current-induced switching and observe the SMR, we sputter 5 nm Pt on 10 nm α-Fe2O3 films and fabricate Hall bars with 4~20 μm width ( Fig.…”

Control of spin‐reorientation transition in (0001) oriented α‐Fe2O3 thin film by external magnetic field and temperature

“…Moreover, these samples were post annealed at 973 K in air for one day. In contrast, our previous report shows we could successfully observed T SR in (0001) oriented α‐Fe 2 O 3 film and T SR can be enhanced above 400 K by Ir doping , without post annealing of the sample. Pressure induced change in spin‐reorientation transition temperature also has been reported around 3.7 ± 0.2 K kbar −1 for both single crystal and powder samples .…”

“…Below T SR , | K FS | > | K MD |, and the spin direction is perpendicular while above T SR , | K MD | > | K FS | and the spin direction is in‐plane. In our earlier report, we demonstrated the suppression of SRT by Ir doping which can enhance spin‐orbit interaction resulting in the enhancement of K FS . Epitaxial α‐Fe 2 O 3 films on Al 2 O 3 substrates have spin‐reorienation transition temperatures that depend on the crystal orientation .…”

“…Recently, there have been numerous efforts in the control of magnetic phase transition temperature by external parameters, for example, Curie temperature of ultrathin Co films by electric field , Neel temperature of a thin CoO film by voltage , Neel temperature of Cr 2 O 3 thin‐films by strain , Morin temperature in α‐Fe 2 O 3 by strain , pressure , and doping , etc. These types of study will escalate the realization of room temperature spintronics devices by tuning the magnetic phase transition temperature of the aforesaid materials above room temperature by external parameters.…”

Reversible hydrogen control of antiferromagnetic anisotropy in α-Fe2O3

“…Consequently, reversible engineering of the anisotropy, and thereby the Morin transition, is crucial as it would allow control over magnon-transport 20,21 and topological texture dimensions 22 . Previous reports have shown that strain 25 , chemical doping 19,[26][27][28][29][30] and meso-structure 31 can modify the antiferromagnetism in α-Fe 2 O 3 . However, lack of reversibility and scalability makes these approaches difficult to exploit in practical applications.…”