Muon spin rotation and infrared spectroscopy study of $Ba_{1-x}Na_{x}Fe_{2}As_{2}$

E. Sheveleva; B. Xu; P. Marsik; F. Lyzwa; B. P. P. Mallett; K. Willa; C. Meingast; Th. Wolf; T. Shevtsova; Yu. G. Pashkevich; C. Bernhard

doi:10.1103/physrevb.101.224515

arXiv · 2004.13804

Muon spin rotation and infrared spectroscopy study of $Ba_{1-x}Na_{x}Fe_{2}As_{2}$

E. Sheveleva·B. Xu·P. Marsik·F. Lyzwa·B. P. P. Mallett·K. Willa·C. Meingast·Th. Wolf·T. Shevtsova·Yu. G. Pashkevich·C. Bernhard

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Abstract

The magnetic and superconducting properties of a series of underdoped $Ba_{1-x}Na_{x}Fe_{2}As_{2}$ (BNFA) single crystals with $0.19 \leq x\leq 0.34$ has been investigated with the complementary muon-spin-rotation ($\mu$SR) and infrared spectroscopy techniques. The focus has been on the different antiferromagnetic states in the underdoped regime and their competition with superconductivity, especially for the ones with a tetragonal crystal structure and a so-called double-$Q$ magnetic order. Besides the collinear state with a spatially inhomogeneous spin-charge-density wave (i-SCDW) order at $x=0.24$ and $0.26$, that was previously identified in BNFA, we obtained evidence for an orthomagnetic state with a "hedgehog"-type spin vortex crystal (SVC) structure at $x=0.32$ and $0.34$. Whereas in the former i-SCDW state the infrared spectra show no sign of a superconducting response down to the lowest measured temperature of about 10K, in the SVC state there is a strong superconducting response similar to the one at optimum doping. The magnetic order is strongly suppressed here in the superconducting state and at $x=0.34$ there is even a partial re-entrance into a paramagnetic state at $T<<T_c$.

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E. Sheveleva, B. Xu, P. Marsik, F. Lyzwa, B. P. P. Mallett, K. Willa, C. Meingast, Th. Wolf, T. Shevtsova, Yu. G. Pashkevich, C. Bernhard. 2020-04-28. Muon spin rotation and infrared spectroscopy study of $Ba_{1-x}Na_{x}Fe_{2}As_{2}$. https://doi.org/10.1103/physrevb.101.224515

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