Discovery of magnetoelectric effects in a metal oxide

Physicists show how changes in external magnetic fields and temperatures simultaneously influence the magnetic and electric polarization of cupric oxide, a building block of high-temperature superconductors¹. 

The scientists say that this discovery, revealing the magnetoelectric effects of cupric oxide, carries potential in the development of materials used in low-power, multi-state memory devices suitable for electrical writing and magnetic readout. 

With the help of various techniques, the physicists from Hochfeld-Magnetlabor Dresden, Germany, Institució Catalana de Recerca i Estudis Avançats, Spain, and the American University of the Middle East, Kuwait, drew phase diagrams of cupric oxide crystals showing new phase transitions and magnetic structures under the influence of external magnetic fields. 

The findings show that magnetic fields suppressed helical modulation of magnetic structure in these crystals. They also dramatically influenced the crystals’ electric polarization, which is the distortion of electronic clouds away from atomic nuclei — a phenomenon also known as ‘multiferrocity’.  

At about −60 degree Celsius, an application of modest magnetic field induced a phase transition in the metal oxide, converting paraelectric magnetic structure into ferroelectric one. “But magnetic fields with higher intensities close to 50 Tesla caused this phase to disappear, resulting in remarkable changes in electric polarization,” says principal investigator Vassil Skumryev.

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