Robust charge and magnetic orders under electric field and current in multiferroic LuFe_2O_4

摘要

We performed elastic neutron-scattering measurements on the charge and magnetically ordered multiferroic material LuFe_2O_4. An external electric field along the [001] direction with strength up to 20 kV/cm applied at low temperature (～100 K) does not affect either the charge or magnetic structure. At higher temperatures (～360 K), before the transition to three-dimensional charge-ordered state, the resistivity of the sample is low, and an electric current was applied instead. A reduction in the charge and magnetic peak intensities occurs when the sample is cooled under a constant electric current. However, after calibrating the real sample temperature using its own resistance-temperature curve, we show that the actual sample temperature is higher than the thermometer readings, and the "intensity reduction" is entirely due to internal sample heating by the applied current. Our results suggest that the charge and magnetic orders in LuFe_2O_4 are unaffected by the application of external electric field and current, and previously observed electric-field and current effects can be naturally explained by internal sample heating.