Anomalous critical behavior of NaV2O5

The temperature dependences and critical behavior of the dielectric constant were studied in NaV2O5 along the c axis in a frequency range of 1 MHz-1GHz and a temperature range of 4.2–300 K. An analysis of the data obtained, along with literature data on the heat capacity, magnetic losses, and the ultrasound velocity, indicates that the various physical quantities demonstrate similar temperature dependences in the vicinity of the transition, which corroborates the conclusion on the universality of the critical behavior in NaV2O5. Deviations from the predictions of the standard theory of second-order phase transitions were found, such as the asymmetry of the critical behavior above and below the transition and the presence of an anomalous base line.