Recent experiments in optimally hole-doped iron arsenides have revealed a novel magnetically ordered ground state that preserves tetragonal symmetry, consistent with either a charge-spin density wave (CSDW), which displays a nonuniform magnetization, or a spin-vortex crystal (SVC), which displays a noncollinear magnetization. Here we show that, similarly to the partial melting of the usual stripe antiferromagnet into a nematic phase, either of these phases can also melt in two stages. As a result, intermediate paramagnetic phases with vestigial order appears: a checkerboard charge density wave for the CSDW ground state, characterized by an Ising-like order parameter, and a remarkable spin-vorticity density wave for the SVC ground state - a triplet d-density wave characterized by a vector chiral order parameter. We propose experimentally detectable signatures of these phases, show that their fluctuations can enhance the superconducting transition temperature, and discuss their relevance to other correlated materials.
Bibliographical noteFunding Information:
U.S. Department of Energy http://dx.doi.org/10.13039/100000015 Department of Energy DOE http://sws.geonames.org/6252001/ http://sws.geonames.org/4138106/ DE-SC0012336 DE-AC02-76SF00515 United States - Israel Binational Science Foundation http://dx.doi.org/10.13039/100006221 BSF http://sws.geonames.org/294640/ National Science Foundation http://dx.doi.org/10.13039/100000001 NSF http://sws.geonames.org/6252001/ http://sws.geonames.org/6254928/ PHY-1066293 We thank C. Batista, A. Boehmer, A. Chubukov, J. Kang, C. Meingast, R. Osborn, M. Schuett, and X. Wang for fruitful discussions. R.M.F. is supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, under Award No. DE-SC0012336. S.A.K. is supported by the U.S. Department of Energy under Contract No. DE-AC02-76SF00515. E.B. was supported by the Israeli Science Foundation, by the US-Israel Binational Science Foundation, and by an Alon fellowship. We thank the hospitality of the Aspen Center for Physics, where this work was initiated. The Aspen Center for Physics is supported by National Science Foundation Grant No. PHY-1066293.