High field optical response of eta-Mo4O11

We report the polarized optical reflectance of quasi-two-dimensional eta-Mo 4O11 in a perpendicular magnetic field up to 30 T at 4.2 K. The in-field me asurements are done on the conducting be plane covering the 6000-26000 cm(- 1) energy range. The absolute reflectance shows a free: carrier response in the near infrared and two electronic transitions in the optical regime: an intraband transition (d -> d) near 12000 cm(-1) and a charge transfer (oxy gen p -> molybdenum d) near 30000 cm(-1). In the magnetic field, no change in the normalized reflectance is observed in the intraband transition range through the 20 T Landau transition, whereas a notable deviation from unity is observed on the low-energy side of the charge transfer transition along both b and c polarizations. We discuss the results in,terms of the effect of the magnetic field on the electronic structure and quantum limit respons e of eta-Mo4O11.