Sign reversal of anisotropic magnetoresistance in La0.7Ca0.3MnO3/SrTiO3 ultrathin films

We present the observation of strain induced sign reversal of anisotropic magnetoresistance (AMR) in La0.7Ca0.3MnO3 (LCMO) ultrathin films (thickness ∼ 4 nm) deposited on SrTiO3 (001) substrate (STO). We have also observed unusually large AMR (∼24%) in LCMO/STO thin films with thickness of 6 nm below but close to its Curie temperature (TC) which decreases as the film thickness increases. The sign reversal of AMR (with a maximum value of −6%) with magnetic field or temperature for the 4 nm thin film may be attributed to the increase in tensile strain in the plane of the thin film which in turn facilitates the rotation of the magnetization easy axis.

[1]  A. Tulapurkar,et al.  Optimization of La0.7Sr0.3MnO3 thin film by pulsed laser deposition for spin injection , 2014 .

[2]  L. You,et al.  Oxygen-driven anisotropic transport in ultra-thin manganite films , 2013, Nature Communications.

[3]  Wei He,et al.  Determination of magnetic anisotropy constants in Fe ultrathin film on vicinal Si(111) by anisotropic magnetoresistance , 2013, Scientific Reports.

[4]  Yiwei Liu,et al.  Strain induced tunable anisotropic magnetoresistance in La0.67Ca0.33MnO3/BaTiO3 heterostructures , 2013 .

[5]  K. Chow,et al.  ANISOTROPIC MAGNETORESISTANCE IN PEROVSKITE MANGANITES , 2011 .

[6]  V. Markovich,et al.  Anisotropic magnetoresistance in low-doped La0.79Ca0.21MnO3 crystals , 2011 .

[7]  Zongxin Zhang,et al.  Angular dependent magnetoresistance with twofold and fourfold symmetries in A-type antiferromagnetic Nd0.45Sr0.55MnO3 thin film , 2010 .

[8]  B. Alascio,et al.  Anisotropic magnetoresistance in manganites: experiment and theory , 2009, Journal of physics. Condensed matter : an Institute of Physics journal.

[9]  T. Zhao,et al.  Crossover of angular dependent magnetoresistance with the metal-insulator transition in colossal magnetoresistive manganite films , 2009 .

[10]  K. Chow,et al.  Dramatic strain induced modification of the low field anisotropic magnetoresistance in ultrathin manganite films , 2008 .

[11]  K. Chow,et al.  Magnetoresistive anisotropy and magnetoresistivity in strained La0.65Ca0.35MnO3 films near the metal-insulator transition , 2007 .

[12]  S. Pennycook,et al.  Strain induced phase separation in La0.67Ca0.33MnO3 ultra thin films , 2006 .

[13]  Y. Tokura.  Colossal Magnetoresistive Oxides , 2000 .

[14]  C. Chien,et al.  Low-field magnetoresistance anisotropy in ultrathin Pr0.67Sr0.33MnO3 films grown on different substrates , 1999 .

[15]  J. Eckstein,et al.  Anisotropic magnetoresistance in tetragonal La1−xCaxMnOδ thin films , 1996 .

[16]  H. Pfeiffer,et al.  Temperature dependence of the magnetization in fine particle systems and the Hopkinson effect. Application to barium ferrite powders , 1994 .