I review theoretical ideas and implications of experiments for the gap structure and symmetry
of the Fe-based superconductors. Unlike any other class of unconventional …

Since the discovery of iron-based superconductors, a new chapter has been opened in the
history of the development of high temperature superconductivity. In the past decade, there …

We present detailed measurements of the temperature-dependent Raman spectra of
optimally doped Ba 0.6 K 0.4 Fe 2 As 2 and analyze the low-temperature spectra based on …

The iron-based superconductors A Fe 2 As 2 with A= K, Rb, Cs exhibit large Sommerfeld
coefficients approaching those of heavy-fermion systems. We have investigated the …

The symmetry of the pairing state in iron pnictide superconductor Ba 1− x K x Fe 2 As 2 is
still controversial. At optimal doping (x≈ 0.4), it is very likely s wave, but for x= 1 there are …

We show that superconductors with broken time-reversal symmetry have very specific
magnetic and electric responses to inhomogeneous heating. A local heating of such …

We analyze the s+ is state that is proposed as a candidate superconducting state for strongly
hole-doped Ba 1− x K x Fe 2 As 2. Such a state breaks time-reversal symmetry (TRS) but …

We report measurements of electrical resistivity under pressure to 5.8 GPa, magnetization to
6.7 GPa, and ac susceptibility to 7.1 GPa in K Fe 2 As 2. The previously reported change of …

Starting with the generic Ginzburg–Landau expansion from a microscopic N-band model,
we focus on the case of a 3-band model which was suggested to be relevant to describe …

We report a sudden reversal in the pressure dependence of T c in the iron-based
superconductor RbFe 2 As 2, at a critical pressure P c= 11 kbar. Combined with our prior …