Electric field control of magnetization in Y-type hexaferrite single crystals close to room-temperature

Y-type hexaferrites with trigonal structure offer a rich variety of non-colinear magnetic phases, among them the most interesting is the ferrimagnetic and ferroelectric FE3 phase. In the Al-doped Y-type hexaferrite, (Ba,Sr)₂Co₂Fe₁₁AlO₂₂, the FE3 phase can be stabilized as a metastable state close to room temperature, as shown by neutron diffraction and magnetic field induced polarization measurements.
Here we demonstrate that by appropriate chemical doping the FE3 phase can be stabilized as a further step towards room temperature magnetoelectric memory devices. Based on further static magnetization and neutron diffraction measurements, we show that the FE3 state coexists as a stable phase with other magnetoelectric and non-magnetoelectric phases even without poling fields. With oxygen annealing treatment it was possible to drastically increase the resistivity of the samples making it possible to carry out magnetoelectric measurements at high temperatures. Owing to the prominent stability of the FE3 phase, magnetic field induced ferroelectricity and electric field control of magnetization was successfully demonstrated close to room temperature. In the M-E experiments we have found remanent magnetization reversal, which has dominant importance in the future technical applications.