Magnetization depinning transition, anisotropic magnetoresistance and inplane anisotropy in two polytypes of La${}_{2/3}$Sr${}_{1/3}$MnO${}_3$ epitaxial films

Abstract

The isothermal magnetoresistance [R($\theta$)] of [001] and [110] epitaxial films of La${}_{2/3}$Sr${}_{1/3}$MnO${}_3$ measured as a function of the angle $\theta$ between current ($\vec{I}$) and magnetic field ($\vec{H}$), both in the plane of the film, is measured at several temperatures between 10 and 300K. The magnetic easy axis of these polytypes is intimately related to the orientation of Mn - O - Mn bonds with respect to the crystallographic axis on the plane of the substrate and energy equivalence of some of these axes. The magnetization vector ($\vec{M}$) of the [001] and [110] type films is pinned along the [110] and [001] directions respectively at low fields. A magnetization orientation phase transition (MRPT) which manifests itself as a discontinuity and hysteresis in $R(\psi )$ where $\psi$ is the angle between $\vec{H}$ and the easy axis for the $\vec{H}$ below a critical value ${\vec{H}}^{\ast }$ has been established. The boundary of the pinned and depinned phase on the H-T plane has been established. The highly robust pinning of magnetization seen in [110] films is related to their uniquely defined easy axis. The isothermal resistance R${}_{\perp }$ and R${}_{\Vert }$ for $\vec{I}\perp \vec{H}$ and $\vec{I}\Vert \vec{H}$, respectively for both polytypes follows the inequality R${}_{\perp }>$ R${}_{\Vert }$ for all ranges of fields ($0\le H\le 3500Oe$) and temperatures (10K - 300K). A full fledged analysis of the rotational magnetoresistance is carried out in the framework of Döring theory for MR in single crystal samples. Strong deviations from the predicted angular dependence are seen in the irreversible regime of magnetization.

20 pages, 16 figures

References in corpus (2)

• The origin of high transport spin polarization in La${}_{0.7}$Sr${}_{0.3}$MnO${}_3$: direct evidence for minority spin states
• Superconducting and normal-state interlayer-exchange-coupling in La${}_{0.67}$Sr${}_{0.33}$MnO$3$-YBa${}_2$Cu${}_3$O${}_7-La$_{0.67}$Sr$_{0.33}$MnO${3}$ epitaxial trilayers

Cited by in corpus (4)

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• Tailoring exchange bias in half-metallic La${}_{2/3}$Sr${}_{1/3}$MnO${}_3$ thin films for spin-valve applications
• Magnetoresistance studies of $L{a}_{2/3}S{r}_{1/3}Mn{O}_3$ - $YB{a}_{2}C{u}_3{O}_7$ - $L{a}_{2/3}S{r}_{1/3}Mn{O}_3$ trilayers with ferromagnetic coupling along the nodal direction of $YB{a}_{2}C{u}_3{O}_7$
• A comparative study of angle dependent magnetoresistance in [001] and [110] $L{a}_{2/3}S{r}_{1/3}Mn{O}_3$