We report observation of strong magnetic proximity coupling in a heterostructured superconductor Sr2VO3FeAs, determined by the upper critical fields Hc2(T) measurements up to 65 T. Using the resistivity and the radio-frequency measurements for both H∥ab and H∥c, we found a strong upward curvature of Hc2c(T), together with a steep increase of Hc2ab(T) near Tc, yielding the anisotropic factor γH=Hc2ab/Hc2c up to ∼ 20, the largest value among iron-based superconductors. These are attributed to the Jaccarino-Peter effect, rather than to the multiband effect, due to strong exchange interaction between itinerant Fe spins of the FeAs layers and localized V spins of Mott-insulating SrVO3 layers. These findings provide evidence for strong antiferromagnetic proximity coupling, comparable with the intralayer superexchange interaction of SrVO3 layer and sufficient to induce magnetic frustration in Sr2VO3FeAs.
@article{arxiv.2010.01752,
title = {Strong antiferromagnetic proximity coupling in a heterostructured superconductor Sr$_2$VO$_3$FeAs},
author = {Jong Mok Ok and Chang Il Kwon and O. E. Ayala Valenzuela and Sunghun Kim and Ross D. McDonald and Jeehoon Kim and E. S. Choi and Woun Kang and Y. J. Jo and C. Kim and E. G. Moon and Y. K. Kim and Jun Sung Kim},
journal= {arXiv preprint arXiv:2010.01752},
year = {2020}
}