Spin dynamics and relaxation in 7.6 nm thin film of La0.7Sr0.3MnO3/SrTiO3: ac magnetic susceptibility and magnetic viscosity investigations
- West Virginia Univ., Morgantown, WV (United States)
- Univ. of Connecticut, Storrs, CT (United States)
Analysis of the results from our investigations of the temperature dependence of ac susceptibilities (χ' and χ'') and magnetic viscosity in a 7.6 nm thin film of La0.7Sr0.3MnO3 grown on SrTiO3 (001) substrate is presented. The Curie temperature (TC) of this film is magnetic field (H) dependent, varying as [TC(H) - TC(0)] ~ Hn with TC(0) = 270 K and n = 0.15. Temperature dependence of χ' and χ'' measured at ac frequencies fm in the range of 0.1–10 kHz shows a broad peak near 230 K associated with the blocking temperature (TB) of spin clusters present in the 1.4 nm surface layer and a frequency dependent peak near 270 K associated with TC. The mean relaxation time τ determined from the Cole–Cole analysis of the temperature dependent χ' and χ'' is shown to fit the Vogel–Fulcher law: τ = τ0 exp[ΔE/kB (T - T0)] with T0 = 245 K, ΔE/kB = 270 K = TC and τ0 = 1.2 x 10-9s. Magnetic viscosity S (measured in H = 0 for a sample cooled in H = 50 Oe) determined from the fit to the magnetization: M (t)= M (0) – S ln t, with time t up to 2 h, shows a peak at 230 K above which M (2 h) switches to negative values for temperatures up to TC(0). It is argued that this negative magnetization results from an interaction between the superparamagnetic spin clusters and the ferromagnetic phase, both being present in the temperature range of TB < T < TC.
- Research Organization:
- West Virginia Univ., Morgantown, WV (United States)
- Sponsoring Organization:
- USDOE; National Science Foundation (NSF); National Aeronautics and Space Administration (NASA)
- Grant/Contract Number:
- SC0016176; DMR-1608656; NNX15AK74A
- OSTI ID:
- 1802852
- Alternate ID(s):
- OSTI ID: 1647891
- Journal Information:
- Journal of Applied Physics, Vol. 128, Issue 7; ISSN 0021-8979
- Publisher:
- American Institute of Physics (AIP)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
Similar Records
Coexistence of considerable inter-particle interactions and spin-glass behavior in La{sub 0.7}Ca{sub 0.3}MnO{sub 3} nanoparticles
Effect of Cu substitution on the magnetic and dielectric properties of La{sub 2}NiMnO{sub 6}