Lattice collapse and the magnetic phase diagram of Sr1-xCaxCo2P2
Abstract
We report that the 122 type Sr1-xCaxCo2P2 solid solution undergoes an anomalous structural transition from the uncollapsed to the collapsed ThCr2Si2 structure at a distinct onset composition near x=0.5. Correlated with the structural changes, the electronic system evolves from a nearly ferromagnetic Fermi liquid to an antiferromagnetic metal, through a complex crossover regime. The structural collapse, driven by P-P bonding across the (Sr,Ca) layers, is much more pronounced in this system than it is in the analogous Fe-based system, indicating a strong sensitivity of structure to total electron count in the transition metal pnictide 122 family.
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