Prefer a chat interface with context about you and your work?
Upper critical field of high-quality single crystals of KFe<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow /><mml:mn>2</mml:mn></mml:msub></mml:math>As<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow /><mml:mn>2</mml:mn></mml:msub></mml:math>
Measurements of temperature-dependent in-plane resistivity, $\rho(T)$, were used to determine the upper critical field and its anisotropy in high quality single crystals of stoichiometric iron arsenide superconductor KFe$_2$As$_2$. The crystals were characterized by residual resistivity ratio, $\rho(300K)/\rho(0)$ up to 3000 and resistive transition midpoint temperature, $T_c$=3.8 K, significantly higher than …