Materials Genome Institute, Shanghai University, Shanghai 200444, China.
Department of Physic, Shanghai University, Shanghai 200444, China.
Sci Rep. 2016 Sep 16;6:33448. doi: 10.1038/srep33448.
We report a spin reorientation from Γ4(Gx, Ay, Fz) to Γ1(Ax, Gy, Cz) magnetic configuration near room temperature and a re-entrant transition from Γ1(Ax, Gy, Cz) to Γ4(Gx, Ay, Fz) at low temperature in TbFe1-xMnxO3 single crystals by performing both magnetization and neutron diffraction measurements. The Γ4 - Γ1 spin reorientation temperature can be enhanced to room temperature when x is around 0.5 ~ 0.6. These new transitions are distinct from the well-known Γ4 - Γ2 transition observed in TbFeO3, and the sinusoidal antiferromagnetism to complex spiral magnetism transition observed in multiferroic TbMnO3. We further study the evolution of magnetic entropy change (-ΔSM) versus Mn concentration to reveal the mechanism of the re-entrant spin reorientation behavior and the complex magnetic phase at low temperature. The variation of -ΔSM between a and c axes indicates the significant change of magnetocrystalline anisotropy energy in the TbFe1-xMnxO3 system. Furthermore, as Jahn-Teller inactive Fe(3+) ions coexist with Jahn-Teller active Mn(3+) ions, various anisotropy interactions, compete with each other, giving rise to a rich magnetic phase diagram. The large magnetocaloric effect reveals that the studied material could be a potential magnetic refrigerant. These findings expand our knowledge of spin reorientation phenomena and offer the alternative realization of spin-switching devices at room temperature in the rare-earth orthoferrites.
我们通过磁化和中子衍射测量报告了 TbFe1-xMnxO3 单晶在室温附近从 Γ4(Gx, Ay, Fz)到 Γ1(Ax, Gy, Cz)的磁构型重取向以及在低温下从 Γ1(Ax, Gy, Cz)到 Γ4(Gx, Ay, Fz)的再进入转变。当 x 约为 0.5~0.6 时，Γ4-Γ1 自旋重取向温度可以提高到室温。这些新的转变与在 TbFeO3 中观察到的众所周知的 Γ4-Γ2 转变以及在多铁性 TbMnO3 中观察到的正弦反铁磁到复杂螺旋磁转变不同。我们进一步研究了磁熵变化(-ΔSM)随 Mn 浓度的演化，以揭示再进入自旋重取向行为和低温下复杂磁相的机制。-ΔSM 在 a 和 c 轴之间的变化表明 TbFe1-xMnxO3 体系中磁晶各向异性能的显著变化。此外，由于 Jahn-Teller 非活性 Fe(3+)离子与 Jahn-Teller 活性 Mn(3+)离子共存，各种各向异性相互作用相互竞争，导致丰富的磁相图。大的磁热效应表明所研究的材料可能是一种潜在的磁制冷材料。这些发现扩展了我们对自旋重取向现象的认识，并为在稀土正铁氧体中实现室温自旋开关器件提供了另一种实现途径。
