Wide critical fluctuations of the field-induced phase transition in graphite

Abstract

In the immediate vicinity of the critical temperature (T${}_c$) of a phase transition, there are fluctuations of the order parameter, which reside beyond the mean-field approximation. Such critical fluctuations usually occur in a very narrow temperature window in contrast to Gaussian fluctuations. Here, we report on a study of specific heat in graphite subject to high magnetic field when all carriers are confined in the lowest Landau levels. The observation of a BCS-like specific heat jump in both temperature and field sweeps establishes that the phase transition discovered decades ago in graphite is of the second-order. The jump is preceded by a steady field-induced enhancement of the electronic specific heat. A modest (20 percent) reduction in the amplitude of the magnetic field (from 33 T to 27 T) leads to a threefold decrease of T${}_c$ and a drastic widening of the specific heat anomaly, which acquires a tail spreading to two times T${}_c$. We argue that the steady departure from the mean-field BCS behavior is the consequence of an exceptionally large Ginzburg number in this dilute metal, which grows steadily as the field lowers. Our fit of the critical fluctuations indicates that they belong to the $3DXY$ universality class, similar to the case of ${}^4$He superfluid transition.

arXiv commentS.M on request

References in corpus (17)

• Critical behavior of the three-dimensional XY universality class
• Three-dimensional quantum Hall effect and metal-insulator transition in ZrTe5
• Quantum limit transport and destruction of the Weyl nodes in TaAs
• Theory of dissipationless Nernst effects
• Sr3Ru2O7: Thermodynamics of Phase Formation in a Quantum Critical Metal
• Two phase transitions induced by a magnetic field in graphite
• Emptying Dirac valleys in bismuth using high magnetic fields
• Possible Excitonic Phase of Graphite in the Quantum Limit State
• Charge density waves in graphite; towards the magnetic ultra-quantum limit
• Tunable excitonic insulator in quantum limit graphite
• Graphite in 90 T: Evidence for Strong-coupling Excitonic Pairing
• Thermodynamic signatures of the field-induced states of graphite
• Ginzburg-Landau theory of phase transitions in quasi-one-dimensional systems
• Fluctuation Study of the Specific Heat of MgB2
• Critical point for Bose-Einstein condensation of excitons in graphite
• Nernst response of the Landau tubes in graphite across the quantum limit
• Ground-state atlas of a three-dimensional semimetal in the quantum limit

Cited by in corpus (2)

• Critical point for Bose-Einstein condensation of excitons in graphite
• Unveiling the double-peak structure of quantum oscillations in the specific heat