Strain modulated magnetic structure in A-type antiferromagnetic Pr_0.5Sr_0.5MnO₃ films

You-Sheng Chen^1*, Jauyn Grace Lin^1,2

¹Center for Condensed Matter Sciences, National Taiwan University, Taipei, Taiwan
²Center for Atomic Initiatives for New Materials, National Taiwan University, Taipei, Taiwan

* Presenter:You-Sheng Chen, email:youshengchen@ntu.edu.tw

The Pr_0.5Sr_0.5MnO₃ (PSMO) is an A-type Antiferromagnetic manganite, consisted of laminar ferromagnetic (FM) layers with antiferromagnetic (AFM) coupling between layers. Recently, we have reported an extraordinary strong crystalline anisotropic magnetoresistance (CAMR) behavior in PSMO thin film [1], which was attributed to the anisotropic field-induced switching of exchange interaction. Previous study indicated the distinct temperature dependencies of CAMR between the two PSMO films under a tensile and a compressive constraint [2]. These two films exhibit metallic and insulator ground state, respectively. However, the mechanism of strain induced metal to insulator transition is still not clear. To understand the strain-related magnetic phases, PSMO films are deposited on single crystals of LaAlO₃(LAO) and 0.3LaAlO₃-0.7 Sr₂TaAlO₆ (LSAT) with pulse laser deposition (PLD). Ferromagnetic resonance (FMR) is applied to investigate the internal field of PSMO. The temperature dependent FMR spectra of PSMO on two different substrates are obtained. The FMR signal of LAO/PSMO appears at 210 K, corresponding to paramagnetic (PM) to FM transition temperature, T_C. Then, the signal enhances until 160 K near the FM-AFM transition T_P. Finally, the signal fades away at 140 K due to the strong AFM interaction. On the other hand, the FMR spectra of LSAT/PSMO show strong signals but with a similar PM-FM-AFM phase transition, in contrast to the regular magnetization bahavior with only PM-FM transition. According to the estimated magnetic anisotropy and analysis of magnetization, our results reveal the short- and long-range ordering in LAO/PSMO and LSAT/PSMO films respectively. The distinct magnetic and electronic transport behaviors are attributed to the different orientations of laminar FM layer because of different substrate constraint.

Reference
[1] Y.S. Chen, J.G. Lin, Applied Physics Letters, 119 (2021)
[2] L.P. Chen, Y.S. Chen, Y.B. Ma, G.J. Lian, Y. Zhang, G.C. Xiong, Journal of Magnetism and Magnetic Materials, 324 (2012) 1189.

Keywords: Manganite, Frustration, Antiferromagnetic, Colossal magnetoresistance