Colossal magnetoresistance over a wide temperature range in Eu0.99La0.01TiO3

TL;DR

This study demonstrates significant magnetoresistance in lightly doped EuTiO3 over a broad temperature range, revealing potential for magnetic field-controlled electronic properties in insulating rare-earth titanates.

Contribution

It reports the first observation of large magnetoresistance in EuTiO3 with La doping, highlighting the role of 4f-3d spin interactions in magnetotransport.

Findings

Magnetoresistance reaches -75% at 2.5 K under 7 T

Significant magnetoresistance persists up to 50 K, well above Neel temperature

Strong exchange coupling between Eu 4f spins and Ti 3d electrons inferred

Abstract

We report occurrence of large magnetoresistance in lightly doped antiferromagnetic paraelectric EuTiO3. Reports of magnetoresistance in rare-earth titanates (RTiO3 oxides) are very scarce because they are highly insulating at low temperatures. EuTiO3 is an insulator at 2.5 K and 1% La3+ substitution for Eu2+ lowers the resistivity over five orders of magnitude at 2.5 K. It is shown that Eu0.99La0.01TiO3 which is antiferromagnetic below T= 5.43 K shows large magnetoresistance over a wide temperature. At 2.5 K, magnetoresistance is -42 % for H = 6 kOe and it increases to -75 % for H = 7 T. Even at 50 K which is ten times higher than Neel temperature, magnetoresistance is very significant (-20 % for H = 7 T). It is suggested that 4f spins on Eu2+ ion is strongly exchange coupled to doped electron in Ti-3d band via f-d interation and field-induced suppression of 4f spin fluctuations decrease spin-disorder scattering experienced by 3d electrons. In view of our results, it will be interesting to investigate magnetoresistance of other rare earth titanates.