  Dissipation inevitably occurs in first order phase transitions, leading to
the irreversible heating. Conversely, the irreversible heating effect could be
a clue for the first order phase transition. We measured the temperature change
at the magnetic-field-induced alpha-theta phase transition of solid oxygen. The
significant temperature increase from 13 to 37 K, amounting to 700 J/mol, is
observed due to the irreversible heating at the first order phase transition.
We argue that the hysteresis loss of the magnetization curve and the
dissipative structural transformation account for the irreversible heating. The
measurement of the irreversible heating can be utilized for detecting the
first-order phase transition in good combination with the ultrahigh magnetic
fields generated in microseconds.
