Magnetization measurement of single La_{0.67}Ca_{0.33}MnO_{3} nanotubes in perpendicular magnetic fields using a micromechanical torsional oscillator

D. ANTONIO; M. I. DOLZ; H. PASTORIZA

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS

ELSEVIER SCIENCE BV

Año: 2010 vol. 322 p. 488 - 493

0304-8853

Using a silicon micromechanical resonator as a sensitive magnetometer, the authors have studied both experimentally and theoretically the magnetic behavior of two isolated ferromagnetic nanotubes of perovskite La_{0.67}Ca_{0.33}MnO_{3}. The article investigates the specific configuration where a magnetic field H is applied perpendicular to the magnetic easy axis of an isolated nanotube characterized by an uniaxialanisotropy constant K. In this situation, the magnetization M reduces the effective elastic constant k_M of the resonator. This softening of the mechanical system is opposed to the hardening effect of M observedin a previous work, where H was applied parallel to the easy axis. Moreover, in this magnetic field configuration two distinct magnetization regimes are manifested, depending on the magnitude of H. For  H>> 2K/M the magnetization is almost parallel to the applied magnetic field and for H<< 2K/M it is almost parallel to the easy axis of the nanotube. At a certain value of H there is a sharp transition fromone regime to the other, accompanied by a peak in the energy dissipation.