Artificial control of magnetic and magnetoresistive properties in the transition metal oxides superlattices

摘要

Artificial superlattice of LaFeO_3-LaMnO_3 (LFO-LMO) have been formed on SrTiO_3(111), (110) and (100) substrates with various stacking periodicity using pulsed laser deposition. [1-3] Their magnetic properties have been controlled by altering the ordering of magnetic ions (Fe or Mn). Charge disproportionate behaviours are also observed in these superlattices. For the superlattices on (111) plane, all the samples showed ferromagnetic (or ferrimagnetic) behaviors and the same Curie temperature of 230K. In the case of other superlattices formed on (110) and (100), oh the other hand, the increase of the spin frustration effect between LFO-LMO interface with decrease of the stacking periodicity casues reduction of Tc and magnetization. [4] Specially, spin galss like behaviours observed in the superlattices of less than 3/3 stacking periodicity Furthermore, we have constructed low dimensional (1D) superlattices with a sequence of SrRuO_3 and SrTiO_3 or BaTiO_3 on the (110) surface. In this system, magnetic and conducting properties have been controlled by the low dimensionality. Spin Pierls and/or Haldane gap behavior is expected in these pseudo-1D superlattices.