DQMP Seminar - Thermodynamic and transport properties of graphite at high magnetic field

03.04.2018 13:00 – 14:30

When a magnetic field confines the carriers of a Fermi sea to their lowest Landau level, electron-electron interactions are expected to play a significant role in determining the electronic ground state. Three decades ago it has been shown that graphite host a field-induced state driven by such interactions [1]. Here we will discuss our magneto-transport and ultra sound measurements at high magnetic field. Studying the magnetoresistance in graphite up to 80 T, we find that the magnetic field induces two successive phase transitions consisting of two distinct ordered states each restricted to a finite field window. In both states, an energy gap opens up in the out-of-plane conductivity and coexists with an unexpected in-plane metallicity for a fully gap bulk system. Such peculiar metallicity may arise as a consequence of edge-state transport expected to develop in the presence of a bulk [2]. The evolution of elastic constant anomalies with temperature and magnetic field across the first order state shows that it evolves in a sequence of 2nd order and first order thermodynamic phase transitions [3]. The complete phase diagram of graphite at high magnetic field will be discuss. If time allows I will also discuss the observation of magnetoconductance oscillations periodic in magnetic field with an amplitude of the order of $\frac{e^2}{h}$ in macroscopic samples of highly oriented pyrolytic graphite (HOPG) which can be explained by invoking moir\'e superlattices with a discrete distribution in periodicity [4].

[1] S. Tanuma et al., in Physics in High Magnetic Fields, ed. S. Chikazumi and N. Miura (Springer, Berlin 1981))
[2] B.Fauqu\'e et al., Phys. Rev. Lett., {\bf{110}}, 266601 (2013)
[3] D. Le Boeuf et al., Nat Com, {\bf{8}}, 1337 (2017)
[4] C. W. Rischau et al., Phys. Rev. B {\bf{95}}, 085206 (2017)

Lieu

Bâtiment: Ecole de Physique

Auditoire Stückelberg

Organisé par

Département de physique de la matière quantique

Intervenant-e-s

Benoît Fauqué, Dr, ESPCI, Paris

entrée libre