Orbital-dependent charge dynamics in MnP revealed by optical study
  Unconventional superconductivity often emerges at the border of long-range magnetic orders. Understanding the low-energy charge dynamics may provide crucial information on the formation of superconductivity. Here we report the unpolarized/polarized optical conductivity study of high quality MnP single crystals at ambient pressure. Our data reveal two types of charge carriers with very different lifetimes. In combination with the first-principles calculations, we show that the short-lifetime carriers have flat Fermi sheets which become gapped in the helimagnetic phase, causing a dramatic change in the low-frequency optical spectra, while the long-lifetime carriers are anisotropic three-dimensional like which are little affected by the magnetic transitions and provide major contributions to the transport properties. This orbital-dependent charge dynamics originates from the special crystal structure of MnP and may have an influence on the unconventional superconductivity and its interplay with helimagnetism at high pressures. 
P. Zheng, Y. J. Xu, W. Wu, G. Xu, J. L. Lv, F. K. Lin, P. Wang,   Yi-feng Yang, and J. L. Luo
cond-mat.supr-con cond-mat.str-el