Correlation between crystal structure and magnetic properties in La1-xSrxMnO3 nano-particles for x=0.1~0.4.
Y. S. Chen (陳友生)1*, K. L. Liang (梁凱玲)1, J. G. Lin (林昭吟)*1
1Center for Condensed Matter Sciences, National Taiwan University, Taipei, Taiwan
* presenting author:You-Sheng Chen, email:youshengchen@ntu.edu.tw
Mixed-valence magnites exhibit double exchange interaction between Mn3+ and Mn4+ which induces simultaneously metallic and ferromagnetic (FM) transitions. This magnetic dependent conducting property results in colossal magnetoresistance (CMR) effect. Among these half-doped magnites, Sr doped LaMnO3 (La1-xSrxMnO3, LSMO) attracts intensive attention for the room-temperature ferromagnetism and high conductivity at x=0.2~0.4. The applications of CMR devices and the electrodes for fuel/solar cells has been proposed.1, 2, 3
Due to the strong interaction between magnetic and conductivity incorporating with structure transitions, LSMO shows a rich phase diagram. The distortion of crystal structure is reported in nano-grained LSMO4 for x=0.125, which affects the magnetic transitions. Recently the ferromagnetic transition and CMR of LSMO nanoparticles with x=0.1 was reported to occur at room-temperature which is much higher than the TC of bulk sample (~150K). This distinct difference between nano-particle and bulk raises an issue of doping induced structural effects on magnetism for nano-sized LSMO. However, the x dependent study on nano-particle is very rare in this field.
In this works, LSMO nano-particles with x=0.1, 0.2, 0.3 and 0.4 are prepared with sol-gel method. High energy X-ray diffraction (XRD) is applied to identify the structures of LSMO nano-particles. The particle size of around 16~19 nm and the nominal composition are confirmed with scanning electron microscope and inductively coupled plasma atomic emission spectroscopy. XRD results indicate a rhombohedral symmetry for all samples different from that of bulk materials which are well known having an orthorhombic to rhombohedral transition from x=0.1 to 0.2. Temperature and field-dependent magnetization are measured for all samples. The doping dependence of magnetic properties in nanoparticles is also different from the results of bulk sample. Combining the structural and magnetic results, it prevails that the magnetic transition temperature is correlated with the structure distortion which might be originated from the variation of Mn-Mn exchange coupling in nano-sized LSMO.
+ This work is financial supported by Minister of Science and Technology of R. O. C. with the project no. NSC102-2112-M-002-MY3


*jglin@ntu.edu.tw

1.A-M Haghiri-Gosnet and et al., J. Phys. D: Appl. Phys. 36 R127 (2003)
2.Chun-Lin Chu and et al., International Journal of Hydrogen Energy, 33, 10 (2008)
3.Yongfeng Zhong and et al., Appl. Phys. Letters, 106, 263903 (2015)
4.Anulekha Dutta and et al., Phys. Rev. B 68, 054432 (2003)


Keywords: LSMO, Half-metal, soft magnet, pervoskite, colossal magnetoresistance