Ultrafast control of ferroelectric anisotropy at room temperature in LuFe2O4*

In electronic ferroelectrics, wherein spontaneous polarization P is realized by charge ordering (CO) arising from inter-site Coulomb repulsion, ultrafast/large electronic responses are expected therein. Layered iron oxides LuFe2O4 is promising candidates toward practical applications for showing the ferroelectric CO at room temperature [1, 2]. Here we report highly-sensitive nature of the ferroelectric polarization P at room temperature; the concomitant second harmonic generation (SHG) has been found to show the largest (ca. 150%) increase among bulk ferroelectrics upon applying 100 kV/cm-class THz electric field. Ultrafast modulation of the anisotropy of the ferroelectric polarization is discussed based on the THz-field induced change of the SHG anisotropy. Phase-sensitive responses of 2’d order nonlinear susceptibility (d-tensor) show that the sensitivity is increasing during the THz-field application, reflecting the cooperativity.

[1] N. Ikeda et al., Nature 436, 1136 (2005).

[2] K. Fujiwara et al., Sci. Rep. 11, 4277 (2021).