This interesting physical phenomenon is normally called the charge heating effect. In some cases, there exists a simple effective charge temperature-current relation T c ∝ I α , where α is an exponent that depends on charge-phonon scattering [8]. It is now well established that the two-bath
model can be used to describe charge heating and charge energy loss rate by charge-phonon scattering [8]. The charge heating effect has become increasingly important as device dimensions are reduced and charge mobility is increased [9]. In particular, Dirac fermion heating in graphene is an important physical phenomenon since it affects thermal dissipation and heat management in modern electronics [10] and low-temperature applications INK 128 such as quantum resistance metrology [11]. Insulator-quantum Hall (I-QH) OSI-906 supplier transition [12–15] is an interesting physical
phenomenon in the field of 2D physics. Especially, a direct transition from an insulator to a high Landau level filling factor ν ≥ 3 QH state which is normally described as the direct I-QH transition continues to attract interest [16–18]. Very recently, eFT508 ic50 experimental evidence for direct I-QH transition in epitaxial monolayer graphene [19] and in mechanically exfoliated multilayer graphene [20] has been reported. In order to further study direct I-QH transition in the graphene-based system, one may wish to investigate Dirac fermion heating in graphene. Moreover, it is a fundamental issue to see if a current-independent point in the longitudinal resistivity when the bath temperature is fixed exists since such a point should be equivalent to the direct I-QH transition. Furthermore, one could probe current scaling on both sides of the direct I-QH transition to further study Dirac fermion-phonon scattering as well as Dirac fermion-Dirac fermion scattering, both of which Selleck Depsipeptide are very fundamental physical phenomena. In this paper, we report magnetotransport measurements on multilayer epitaxial graphene of few layers obtained under conditions which favor controlled growth at high temperatures [21]. Dirac fermion heating in the high current limit is studied. It is found
that in the low magnetic field regime, the effective Dirac fermion temperature obeys a simple power law T DF ∝ I ≈0.5. Such results suggest that the Dirac fermion-phonon scattering rate 1/τ DFP ~ T 2, consistent with those in conventional 2D electron systems. With increasing magnetic field, interestingly, a current-independent point in the longitudinal resistivity is observed. It was demonstrated that such a point corresponds to the direct I-QH transition characterized by a T-independent point in ρ xx. This result is further supported by the vastly different I dependences for both sides of the I-QH transition. Our new experimental results, together with recent experimental results [19, 20], indicate that direct I-QH transition is a universal effect in graphene.