Lattice coupled first order magnetoresistance transition in an A-type antiferromagnet: Pr${}_{0.46}$Sr${}_{0.54}$MnO${}_3$

Abstract

We investigated magnetic, magnetotransport and magnetostriction properties of the A-type antiferromagnet Pr${}_{0.46}$Sr${}_{0.54}$MnO${}_3$ which undergoes a first order paramagnetic-antiferromagnetic transition below T${}_N$ = 210 K while cooling and T${}_N$ = 215 K while warming. The zero field ($\hat{I}{¼}_0$H = 0 T) resistivity shows a sudden jump at T${}_N$ and a small bump around T${}_{max}$ = 220 K (\TEXTsymbol{>} T${}_N$). T${}_N$ shifts down and T${}_{max}$ shifts up with increasing $\hat{I}{¼}_0$H. Magnetoresistance as high as -45-57 % at 7 T is found in the temperature range 180 K-230 K. Isothermal measurements indicate that the field induced antiferromagnetic to ferromagnetic transition below T${}_N$ is accompanied by a rapid decrease of the resistivity but increase of volume ($\hat{I}”$V/V = +0.25 % at 180 K and 13.7 T). This lattice coupled magnetoresistance transition is suggested due to the field induced structural transition from the low volume orthorhombic to the high volume tetragonal structure.

10 pages, 5 figures, submitted to Phys. Rev. B