Colossal Magnetoresistance without Mixed Valence in a Layered Phosphide Crystal.
basic_science · Level V
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- Record sourced from PubMed, PMID 33511677.
- Also identified by DOI 10.1002/adma.202005755.
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Abstract
Materials with strong magnetoresistive responses are the backbone of spintronic technology, magnetic sensors, and hard drives. Among them, manganese oxides with a mixed valence and a cubic perovskite structure stand out due to their colossal magnetoresistance (CMR). A double exchange interaction underlies the CMR in manganates, whereby charge transport is enhanced when the spins on neighboring Mn<sup>3+</sup> and Mn<sup>4+</sup> ions are parallel. Prior efforts to find different materials or mechanisms for CMR resulted in a much smaller effect. Here an enormous CMR at low temperatures in EuCd<sub>2</sub> P<sub>2</sub> without manganese, oxygen, mixed valence, or cubic perovskite structure is shown. EuCd<sub>2</sub> P<sub>2</sub> has a layered trigonal lattice and exhibits antiferromagnetic ordering at 11 K. The magnitude of CMR (10<sup>4</sup> %) in as-grown crystals of EuCd<sub>2</sub> P<sub>2</sub> rivals the magnitude in optimized thin films of manganates. The magnetization, transport, and synchrotron X-ray data suggest that strong magnetic fluctuations are responsible for this phenomenon. The realization of CMR at low temperatures without heterovalency leads to a new regime for materials and technologies related to antiferromagnetic spintronics.