D-wave gap

Meulen et al. 1988a,b, Junod 1996). This indicates that some conduction electrons do not pair at low temperatures, most likely due to an anisotropic or d-wave gap (i.e., with nodes). The lattice specific heat at temperatures not exceeding 10% of the Del e temperature can be approximated by The Debye temperature for R123x lies between 350 and 450 K and /S = 0.3-0.5 mJmole (van der Meulen et al. 1988a,b, Junod 1996). In most of... 

Ichimura K, Takami M, Nomura K (2008) Direct observation of d-wave superconducting gap in /c-(BEDT-TTP)2Cu[N(CN)2]Br with scanning tunneling microscopy. J Phys Soc Jpn 77 114707/1-6... 

Concerning the manifestation of various gaps of the model, the Ey excitations become attributed to the hot spectrum. The cold spectrum is usually considered as nongapped [28,49], If one takes account of this by multiplying the defect subsystem Aa by a d-wave symmetry factor, the cold spectrum becomes empty. At c < cp the appearance of two pseudogaps is expected. In the basic optimal doping region (c> Cp, c < c0) the spectrum... 

It was shown then that all these observed features can be described self-consistently by Fermi-liquid model for quasiparticles in clean d-wave superconductor with resonant intralayer scattering [14]. The superconducting gap is expressed as A([Pg.185]

Despite the previously debated d-wave symmetry of the superconducting gap in YNi2B2C as suggested from the interpretation of specific-heat (Cp) data (Nohara et al., 1997), additional mechanisms for the T3 dependence of the electronic part of Cp and its unusual magnetic-field dependence were discussed, including the shrinking of the vortex core radius with increasing field (Nohara et al., 1999). The influence of disorder is discussed in Section 6.2. Measurements of the microwave... 

By plotting a against temperature for the four fields studied,9 H = 0.05, 1.0, 3.0 and 6.0 Tesla, one finds qualitatively similar features to previous data (see e.g., Ref. 10), but also certain features that rule out d-wave pairing, and which provide clues regarding the extrinsic effects (i.e., effects not directly associated with the gap function symmetry) that play a role in shaping them. Specifically, these data show (i) a distinctive inflection point in cr(T,H) versus temperature near T 20 K, which is most evident at intermediate fields (i.e., H=1.0 and 3.0 Tesla), and is reminiscent of earlier data on Bi2Sr2CaCu20g,4 and (ii) a non-monotonic dependence of the quantity 0,H) on applied magnetic field H. These two effects cannot be adequately explained with either an. v-wavc or a d-wave model alone. 

There seems to be a growing consensus that the superconductivity is d-wave [97], more specifically, dx2 y2 type. Recent microwave measurements [98] would indicate that the penetration depth is linear in temperature, a sign that the gap has zeros. As pointed out in Ref. 99, this does not exclude 5-wave pairing since harmonics of the basic combinations [Eq. (38)] can also lead to zeros of the gap on the Fermi surface. It is interesting to note that d-wave pairing is quite in line with the extrapolations of the two-dimensional Hubbard and t-J models (Section V.B) and the observed competition with AFM. This would point to a spin-exchange mechanism. The parallel with the quasi-one-dimensional superconductors is striking. 

The temperature dependence of Ks at low temperatures is exponential for s-wave pairing. In the case of a d-wave with a line-node gap, the temperature dependence of Ks at low temperatures is linear. Evv ocxvv does not change even below Tc. 

As seen in Fig. 13, the experimental points are located on a single line below Tc. Above 7) this is not the case due to the difference in the Weiss temperatures. Below Tc, 1/7) does not show the coherence peak, but decreases in proportion to T3 except at lower temperatures. The dashed line indicates the calculation based on a two-dimensional d-wave model using the density of states in Fig. 1 with the gap parameter A() = A0 cos 2lower temperatures. The scaling of 1/7) below Tc in Fig. 13 implies that the value of 2A0/ B7). 8 is common for these materials. Similar dependence of 1/7) on temperature is also seen in l70 substituted in the Cu02 plane. Hammel et al. first measured 1/7) of l70 in YBCO7 and found that the temperature dependence of 1/7) for l70 and Cu... 

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