Abstract
The positions of columnar pins and magnetic flux lines determined from a decoration experiment on B${\mathrm{i}}_{2}$S${\mathrm{r}}_{2}$CaC${\mathrm{u}}_{2}$${\mathrm{O}}_{8}$ were used to calculate the distribution of pinning energies in the Bose glass phase. A wide Coulomb gap is found, with effective gap exponent ${s}_{\mathrm{eff}}\ensuremath{\approx}1.2$, as a result of interactions between the vortices. As a consequence, the variable-range hopping transport of flux lines is considerably reduced with respect to the noninteracting case, the effective Mott exponent being enhanced from ${p}_{0}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1/3$ to ${p}_{\mathrm{eff}}\ensuremath{\approx}0.5$ for this sample.
Highlights
The positions of columnar pins and magnetic flux lines determined from a decoration experiment on BSCCO were used to calculate the single–particle density of states at low temperatures in the Bose glass phase
The analogy of flux lines at low temperatures pinned to columnar defects (Bose glass phase) with two–dimensional localized carriers in doped semiconductors (Coulomb glass) [4], suggests that a “Coulomb” gap should emerge in the single–particle density of states
Because such a gap will affect significantly the current–voltage characteristics in a variable range hopping approach [3], it is important to estimate the size of the Coulomb gap in the Bose glass phase and to understand the correlation effects induced by the intervortex repulsion
Summary
The positions of columnar pins and magnetic flux lines determined from a decoration experiment on BSCCO were used to calculate the single–particle density of states at low temperatures in the Bose glass phase. A theory of flux pinning by correlated disorder has been developed to explain these results, exploiting a formal mapping of the statistical mechanics of directed lines onto the quantum mechanics of two–dimensional bosons [3]. The analogy of flux lines at low temperatures pinned to columnar defects (Bose glass phase) with two–dimensional localized carriers in doped semiconductors (Coulomb glass) [4], suggests that a “Coulomb” gap should emerge in the single–particle density of states (distribution of vortex pinning energies).
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