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arXiv · 1803.10588

Collapse of ferromagnetism with Ti doping in Sm$_{0.55}$Sr$_{0.45}$MnO$_3$: A combined experimental and theoretical study

P. Sarkar·N. Khan·K. Pradhan·P. Mandal
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Abstract

We have investigated the effect of Ti doping on the transport properties coupled with the magnetic ones in Sm$_{0.55}$Sr$_{0.45}$Mn$_{1-η}$Ti$_η$O$_3$ ($0 \leq η\leq 0.04$). The parent compound, Sm$_{0.55}$Sr$_{0.45}$MnO$_3$, exhibits a first-order paramagnetic-insulator to ferromagnetic-metal transition just below $T_{\rm c}$ = 128 K. With substitution of Ti at Mn sites ($B$-site), $T_{\rm c}$ decreases approximately linearly at the rate of 22 K$\%^{-1}$ while the width of thermal hysteresis in magnetization and resistivity increases almost in an exponential fashion. The most spectacular effect has been observed for the composition $η$=0.03, where a magnetic field of only 1 T yields a huge magnetoresistance, $1.2 \times 10^7$ $\%$ at $T_c\approx$ 63 K. With increasing magnetic field, the transition shifts towards higher temperature, and the first-order nature of the transition gets weakened and eventually becomes crossover above a critical field ($H_{cr}$) which increases with Ti doping. For Ti doping above 0.03, the system remains insulting without any ferromagnetic ordering down to 2 K. The Monte-Carlo calculations based on a two-band double exchange model show that the decrease of $T_{\rm c}$ with Ti doping is associated with the increase of the lattice distortions around the doped Ti ions.

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P. Sarkar, N. Khan, K. Pradhan, P. Mandal. 2018-03-28. Collapse of ferromagnetism with Ti doping in Sm$_{0.55}$Sr$_{0.45}$MnO$_3$: A combined experimental and theoretical study. https://doi.org/10.1103/physrevb.98.014422

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