Fabrication and characterization of magnetic superlattices-epitaxial Co/Cr(100) and Co/Cr(211) superlattices

Epitaxial Co/Cr superlattices Co(112¯0)/Cr(100) on MgO(100) and Co(11¯00)/Cr(211) on MgO(110) have been grown by molecular beam epitaxy technique. A buffer layer of Mo or CrMo alloy was first deposited on top of the substrate which is crucial to prepare a smooth and well-ordered Cr surfaces and the following superlattices. The epitaxial orientation of Co/Cr(100) superlattices is Co[112¯0]||Cr[100]||MgO[100], Co[11¯00]||Cr[011]||MgO[010] and Co[0001]||Cr[011¯]||MgO[001], while that for Co/Cr(211) is Co[11¯0]||Cr[211]||MgO[110], Co[112¯0]||Cr[1¯11]||MgO[11¯0] and Co[0001]||Cr[011¯]||MgO[001]. (Co_xCr_y) _n superlattices with different Co thickness (x), Cr thickness (y) and number of layers (n) have been deposited. The maximum magnetoresistance of the Co/Cr(211) superlattices is 18% compared with the 4.8% for Co/Cr(100) superlattices. Magnetization measurements also show that antiferromagnetic coupling in Co/Cr(211) superlattices is stronger than in Co/Cr(100) superlattices. The magnetic properties are strongly influenced by the crystal orientation of the multilayers