Pressure-Enhanced Interplane Tunneling Magnetoresistance in a Layered Manganite Crystal

The pressure-induced variations of the anisotropic charge-transport and magnetic properties have been investigated for a bilayered manganite crystal, La_2-2xSr₁₊₂ₓMn₂O₇ ( x0ex0ex=0ex0ex0.3). The magnitude of the magnetic coupling between the adjacent bilayers can be weakened by application of pressure, which makes the charge dynamics more two dimensional (2D) but highly incoherent. As a result, the restoration of the interlayer hopping of the spin-polarized carriers by application of magnetic field, namely the field-induced 2D-3D crossover, gives rise to an extremely high ratio of interplane tunneling magnetoresistance, say, up to Δρc/ρc~4000% at 4.2 K under ~10kbar.