Structural aspects of metamagnetism in Ca_{2-x}Sr_{x}RuO_4 (0.2 < x <   0.5): field tuning of orbital occupation
  The crystal structure of Ca_{2-x}Sr_xRuO_4 with 0.2 < x < 1.0 has been studied by diffraction techniques and by high resolution capacitance dilatometry as a function of temperature and magnetic field. Upon cooling in zero magnetic field below about 25 K the structure shrinks along the c-direction and elongates in the a, b planes (0.2 < x < 1.0), whereas the opposite occurs upon cooling at high-field (x = 0.2 and 0.5). These findings indicate an orbital rearrangement driven by temperature and magnetic field, which accompanies the metamagnetic transition in these compounds. 
M. Kriener, P. Steffens, J. Baier, O. Schumann, T. Zabel, T. Lorenz,   O. Friedt, R. Mueller, A. Gukasov, P. Radaelli, P. Re...