期刊论文详细信息
High density of states in the pseudogap phase of the cuprate superconductor HgBa2CuO4+delta from low-temperature normal-state specific heat
Article
关键词: ELECTRONIC SPECIFIC-HEAT;    FERMI-SURFACE;    QUANTUM OSCILLATIONS;    TRANSPORT-PROPERTIES;    CRITICAL-POINT;    ORDER;   
DOI  :  10.1103/PhysRevB.102.014506
来源: SCIE
【 摘 要 】

The specific heat C of the single-layer cuprate superconductor HgBa2CuO4+delta was measured in an underdoped crystal with T-c = 72 K at temperatures down to 2 K in magnetic fields up to 35 T, a field large enough to suppress superconductivity at that doping (p similar or equal to 0.09). In the normal state at H = 35 T, a residual linear term of magnitude gamma = 12 +/- 2 mJ/K-2 mol is observed in C/T as T -> 0, a direct measure of the electronic density of states. This high value of gamma has two major implications. First, it is significantly larger than the value measured in overdoped cuprates outside the pseudogap phase (p > p*), such as La2-xSrxCuO4 and Tl2Ba2CuO6+delta at p similar or equal to 0.3, where gamma similar or equal to 7 mJ/K-2 mol. Given that the pseudogap causes a loss of density of states and assuming that HgBa2CuO4+delta has the same y value as other cuprates at p similar or equal to 0.3, this implies that gamma in HgBa2CuO4+delta must peak between p similar or equal to 0.09 and p similar or equal to 0.3, namely, at (or near) the critical doping p* where the pseudogap phase is expected to end (p* similar or equal to 0.2). Second, the high gamma value implies that the Fermi surface must consist of more than the single electronlike pocket detected by quantum oscillations in HgBa2CuO4+delta at p similar or equal to 0.09, whose effective mass m* = 2.7m(0) yields only gamma = 4.0 mJ/K-2 mol. This missing mass imposes a revision of the current scenario for how pseudogap and charge order, respectively, transform and reconstruct the Fermi surface of cuprates.

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