Verwey transition in Fe3O4 at high pressure: Quantum critical point at the onset of metallization

We provide evidence for the existence of a quantum critical point at the metallization of magnetite Fe3O4 at pressure p(c)approximate to 8 GPa. We show that the present ac magnetic-susceptibility data support earlier resistivity data. The Verwey temperature scales with pressure T-V similar to(1-p/p(c))(nu) with nu similar to 1/3. The resistivity data show a temperature dependence rho(T)=rho(0)+AT(n) with n similar or equal to 3 above and 2.5 at the critical pressure, respectively. This difference in n with pressure is a sign of critical behavior at p(c). The magnetic susceptibility is smooth near p(c), both at the Verwey transition and near the lower temperature ferroelectric anomaly.