1409.0408v3.pdf (1.48 MB)
Magnetic fluctuations and specific heat in NaxCoO2 near a Lifshitz transition
journal contribution
posted on 2015-07-24, 09:58 authored by Sergey Slizovskiy, Andrey Chubukov, Joseph BetourasJoseph BetourasWe analyze the temperature and doping dependence of the specific heat C(T) in Na x CoO 2 . This material was conjectured to undergo a Lifshitz-type topological transition at x=x c =0.62 , in which a new electron Fermi pocket emerges at the Γ point, in addition to the existing hole pocket with large k F . The data show that near x=x c , the temperature dependence of C(T)/T at low T gets stronger as x approaches x c from below and then reverses the trend and changes sign at x≥x c . We argue that this behavior can be quantitatively explained within the spin-fluctuation theory. We show that magnetic fluctuations are enhanced near x c at momenta around k F , and their dynamics changes between x≤x c and x>x c , when the new pocket forms. We demonstrate that this explains the temperature dependence of C(T)/T . We show that at larger x (x>0.65 ) the system enters a magnetic quantum critical regime where C(T)/T roughly scales as logT . This behavior extends to progressively lower T as x increases towards a magnetic instability at x≈0.75 .
Funding
This work was supported by the EPSRC Grants No. EP/H049797/1 and No. EP/l02669X/1, by the Leverhulme Trust and by the U.S. Department of Energy Grant No. DE-FG02-ER46900.
History
School
- Science
Department
- Physics
Published in
PHYSICAL REVIEW LETTERSVolume
114Issue
6Pages
? - ? (5)Citation
SLIZOVSKIY, S., CHUBUKOV, A. and BETOURAS, J.J., 2015. Magnetic fluctuations and specific heat in NaxCoO2 near a Lifshitz transition. Physical Review Letters, 114, 066403Publisher
© American Physical SocietyVersion
- AM (Accepted Manuscript)
Publisher statement
This work is made available according to the conditions of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) licence. Full details of this licence are available at: https://creativecommons.org/licenses/by-nc-nd/4.0/Publication date
2015Notes
This article was published in the journal, Physical Review Letters [© American Physical Society]. It is also available at: http://dx.doi.org/10.1103/PhysRevLett.114.066403.ISSN
0031-9007Publisher version
Language
- en