New materials for spintronics

Advances in spintronic materials are hampered by interface and defect issues met in thin-film heterostructures that are difficult and expensive to fabricate. Therefore, discovery of new materials exhibiting a spectrum of structural, chemical and physical properties is desirable. We review two novel material classes with promising properties for applications. First, (Ba,Sr)(Fe,Co)_2plusmnxRu_4plusmnxO₁₁ single crystals exhibit long-range ferromagnetic (FM) order at temperatures as high as 490 K, and semiconducting properties well suited for spin injection. Second, we have observed a strongly field-dependent, anisotropic electrical conductivity in bulk single crystals of Ca₃(Ru_1-xCr_x)₂O₇ (0lestimesles0.20), which opens new avenues for understanding the physics of the spin valve effect, and development of devices that do not require precision heterostructures.