Uniaxial Strain and Hydrostatic Pressure Engineering of the Hidden Magnetism in LaCaMnO (0 ≤ ≤ 1/2) Thin Films.

Here, using various substrates, we demonstrate that the in-plane uniaxial strain engineering can enhance the Jahn-Teller distortions and promote selective orbital occupancy to induce an emergent antiferromagnetic insulating (AFI) phase at = 1/3 of LaCaMnO. Such an AFI phase depends not only on the magnitude of epitaxial strain but also on the symmetry of the substrates. Using the large uniaxial strain imparted by DyScO(001) substrate, the AFI ground state is achieved in a wide range of doping levels (0 ≤ ≤ 1/2), leaving an extended AFI phase diagram. Moreover, it is found that hydrostatic pressure can tune the AFI phase back to a hidden ferromagnetic metallic phase, accompanied by the formation of accommodation strain. The coaction of the accommodation strain, uniaxial strain, and hydrostatic pressure produces complex phase competition and evolution, and the result may shed light on phase space control of other functional perovskites with the competing magnetic interactions.