ترغب بنشر مسار تعليمي؟ اضغط هنا

Superconducting and Normal State Properties of Heavily Hole-Doped Diamond

116   0   0.0 ( 0 )
 نشر من قبل Joe Thompson
 تاريخ النشر 2004
  مجال البحث فيزياء
والبحث باللغة English




اسأل ChatGPT حول البحث

We report measurements of the specific heat, Hall effect, upper critical field and resistivity on bulk, B-doped diamond prepared by reacting amorphous B and graphite under high-pressure/high-temperature conditions. These experiments establish unambiguous evidence for bulk superconductivity and provide a consistent set of materials parameters that favor a conventional, weak coupling electron-phonon interpretation of the superconducting mechanism at high hole doping.



قيم البحث

اقرأ أيضاً

To gain insight into the unconventional superconductivity of Fe-pnictides with no electron pockets, we measure the thermal conductivity $kappa$ and penetration depth $lambda$ in the heavily hole-doped regime of Ba$_{1-x}$K$_x$Fe$_2$As$_2$. The residu al thermal conductivity $(kappa/T)_{T rightarrow 0,{rm K}}$ and $T$-dependence of $lambda$ consistently indicate the fully gapped superconductivity at $x=0.76$ and the (line) nodal superconductivity at higher hole concentrations. The magnitudes of $frac{kappa}{T}cdot T_c|_{T rightarrow 0,{rm K}}$ and $frac{dlambda}{d(T/T_c)}$ at low temperatures, both of which are determined by the properties of the low-energy excitations, exhibit a highly unusual non-monotonic x-dependence. These results indicate a dramatic change of the nodal characteristics in a narrow doping range, suggesting a doping crossover of the gap function between the s-wave states with and without sign reversal between $Gamma$-centered hole pockets.
We report a study of the relaxation time of the restoration of the resistive superconducting state in single crystalline boron-doped diamond using amplitude-modulated absorption of (sub-)THz radiation (AMAR). The films grown on an insulating diamond substrate have a low carrier density of about 2.5x10^{21} cm^{-3} and a critical temperature of about 2 K. By changing the modulation frequency we find a high-frequency rolloff which we associate with the characterstic time of energy relaxation between the electron and the phonon systems or the relaxation time for nonequilibrium superconductivity. Our main result is that the electron-phonon scattering time varies clearly as T^{-2}, over the accessible temperature range of 1.7 to 2.2 K. In addition, we find, upon approaching the critical temperature T_c, evidence for an increasing relaxation time on both sides of T_c.
138 - N. Bariv{s}ic , D. Wu , M. Dressel 2010
The electrodynamic properties of Ba(Fe$_{0.92}$Co$_{0.08})_2$As$_{2}$ and Ba(Fe$_{0.95}$Ni$_{0.05})_As$_{2}$ single crystals have been investigated by reflectivity measurements in a wide frequency range. In the metallic state, the optical conductivit y consists of a broad incoherent background and a narrow Drude-like component which determines the transport properties; only the latter contribution strongly depends on the composition and temperature. This subsystem reveals a $T^2$ behavior in the dc resistivity and scattering rate disclosing a hidden Fermi-liquid behavior in the 122 iron-pnictide family. An extended Drude analysis yields the frequency dependence of the effective mass (with $m^*/m_bapprox 5$ in the static limit) and scattering rate that does not disclose a simple power law. The spectral weight shifts to lower energies upon cooling; a significant fraction is not recovered within the infrared range of frequencies.
191 - B. Lv , M. Gooch , B. Lorenz 2009
The normal state and superconducting properties are investigated in the phase diagram of K_xSr_{1-x}Fe_2As_2 for 0<x<1. The ground state upper critical field, H_{c2}(0), is extrapolated from magnetic field dependent resistivity measurements. H_{c2}(0 ) scales with the critical temperature, T_c, of the superconducting transition. In the normal state the Seebeck coefficient is shown to experience a dramatic change near a critical substitution of x=0.3. This is associated with the formation of a spin density wave state above the superconducting transition temperature. The results provide strong evidence for the reconstruction of the Fermi surface with the onset of magnetic order.
The electronic and superconducting properties of Fe1-xSe single-crystal flakes grown hydrothermally are studied by the transport measurements under zero and high magnetic fields up to 38.5 T. The results contrast sharply with those previously reporte d for nematically ordered FeSe by chemical-vapor-transport (CVT) growth. No signature of the electronic nematicity, but an evident metal-to-nonmetal crossover with increasing temperature, is detected in the normal state of the present hydrothermal samples. Interestingly, a higher superconducting critical temperature Tc of 13.2 K is observed compared to a suppressed Tc of 9 K in the presence of the nematicity in the CVT FeSe. Moreover, the upper critical field in the zero-temperature limit is found to be isotropic with respect to the field direction and to reach a higher value of ~42 T, which breaks the Pauli limit by a factor of 1.8.
التعليقات
جاري جلب التعليقات جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
mircosoft-partner

هل ترغب بارسال اشعارات عن اخر التحديثات في شمرا-اكاديميا