Information storage with multiferroics one step closer

HFML research leads to model for predicting magnetic properties of a multiferroic

Measurements in the magnets of the HFML validated a model that predicts the magnetic properties of BiFeO3, a room-temperature multiferroic. Multiferroics are interesting because of their potential applications in electronic information storage. As BiFeO3 is the only material known with mutiferroic properties at room-temperature, it is the best candidate for these applications. The research on BiFeO3 was performed by an international team from Estonia, the United States, and the Netherlands. They published their results in Physical Review Letters on 17 June 2013.

The researchers have studied a cycloidally ordered spin structure in a multiferroic material BiFeO3 and proposed a microscopic model that predicts the spin wave frequencies of BiFeO3 in magnetic field. The close agreement between the theoretical and measured terahertz spectra suggests that the model can provide the foundation for future studies on BiFeO3 and may lay the groundwork for its eventual technological applications.

Due to the coupling between electric and magnetic properties, multiferroic materials are among the most important yet discovered. Applied electric or magnetic field can change the optical properties of a multiferroic and this can be used to build novel switches for terahertz radiation. With a multiferroic material used as a storage medium, information can be written electrically and then read magnetically without Joule heating. Hence, applications of a room-temperature multiferroic would radically transform the microelectronics industry. Because it is the only known room temperature multiferroic, the studied material, BiFeO3 continues to attract intense interest.

Terahertz spectroscopy of spin waves in multiferroic BiFeO3 in high magnetic fields' U. Nagel, Randy S. Fishman, T. Katuwal, H. Engelkamp, D. Talbayev, Hee Taek Yi, S.-W. Cheong, and T. Rõõm. Physical Review Letters, 17 June 2013.

Figure 1
Pseudocubic unit cell of BiFeO3 showing the positions of Bi and Fe ions, the ferroelectric polarization P, three equivalent directions of the cycloidal ordering vector qi, the applied static magnetic field B0 || [001], and the wave vector of incident light k together with the electric field (e) component of light in two orthogonal polarizations that were used in the experiment.