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1

Specific Heat Study of Superconductivity in Cu_{0.061}TiSe_{2}

100%

Kačmarčík J., Pribulová Z., Pal'uchová V., Husaníková P., Karapetrov G., Komanický V., Samuely P.

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vol. 126

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issue 1

322-323

EN

In TiSe_{2} a charge-density-waves order is continuously suppressed by copper doping and superconductivity appears. We report a calorimetric study performed on the superconducting single crystal of Cu_{0.061}TiSe_{2} with T_{c}=2.8 K, measured by the ac technique at low temperatures down to 0.6 K and magnetic fields up to 2 T. Sharp specific heat anomaly at the superconducting transition is found. The temperature dependence of the electronic specific heat and the angular dependence of the critical temperature, measured at a fixed magnetic field, consistently indicate on the existence of a single s-wave superconducting gap with a coupling strength of 2Δ/k_{B}T_{c}=3.6, close to BCS limit.

2

Phase Diagram of TmB_4 Probed by AC Calorimetry

100%

Kačmarčík J., Pribulová Z., Gabáni S., Samuely P., Siemensmeyer K., Shitsevalova N., Flachbart K.

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issue 5

903-904

EN

TmB_4 is a frustrated system based on the Shastry-Sutherland lattice that exhibits complex magnetic properties. In this contribution the magnetic field B vs. temperature T phase diagram of TmB_4 has been studied by ultrasensitive AC calorimetry in the temperature range between 2.9 and 12 K and in magnetic fields up to 8 T. Apart from already known phases our measurements have recognized several new phase transitions suggesting that the phase diagram of TmB_4 is even more complex and deserves further studies.

3

Two-Gap Superconductivity in 2H-NbS_2

84%

Pribulová Z., Leroux M., Kačmarčík J., Marcenat C., Klein T., Rodière P., Cario L., Samuely P.

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issue 5

1024-1025

EN

We performed specific heat measurements of the superconducting single crystal of 2H-NbS_2 in the temperature range down to 0.6 K and magnetic fields up to 14 T. The temperature and magnetic field dependence of the electronic specific heat consistently indicate existence of two superconducting energy gaps in the system. The superconducting anisotropy depends on both temperature and magnetic field. Moreover, the angular dependence of the upper critical field deviates from the Ginzburg-Landau behavior and rather reminds that of MgB_2. All these features point to a multigap superconductivity in 2H-NbS_2. Our measurements are in a perfect agreement with the previous scanning tunneling spectroscopy of Guillamón et al.

4

Local Magnetometry of Cu_{0.064}TiSe_{2}

84%

Pribulová Z., Medvecká Z., Kačmarčík J., Komanický V., Klein T., Husaníková P., Cambel V., Šoltýs J., Karapetrov G., Samuely P.

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vol. 126

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issue 1

370-371

EN

Local magnetometry using miniature Hall-probe array was used to study vortex distribution in superconducting single crystal of Cu_{x}TiSe_{2}, with x=0.064 and T_{c}=3.2 K. We show that vortices after penetration into the sample move towards the center, resulting into a dome-shape field profile. Such a profile is a signature of relatively low pinning. We show that these measured profiles are consistent with a model proposed for the samples in the absence of bulk pinning. Modifications necessary to obtain quantitative agreement between the model and the data are presented.

5

AC Microcalorimetry of Superconducting MgCNi_3 Single Crystals

84%

Kačmarčík J., Pribulová Z., Samuely P., Marcenat C., Klein T., Jang D., Lee H., Lee H., Lee S.

Acta Physica Polonica A

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2008

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vol. 113

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issue 1

363-366

EN

The low-temperature specific heat of single-crystal samples of superconducting MgCNi_3 with typical dimensions 200 μm were measured for the first time. A computer controlled ac microcalorimeter using an optical fiber and an infrared light-emitting diode as the heat source was used down to 2 K at magnetic fields up to 8 T. The specific heat data suggest a moderate coupling in MgCNi_3.

6

Point-Contact Spectroscopy of Superconducting MgCNi_3 Single Crystals

84%

Pribulová Z., Szabó P., Kačmarčík J., Samuely P., Jang D., Lee H., Lee H., Lee S.

Acta Physica Polonica A

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2008

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vol. 113

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issue 1

215-218

EN

The first point-contact spectroscopy measurements on MgCNi_3 single crystals of very good quality are presented. The measurements have been performed in the temperature range from 1.5 K up to 10 K and at magnetic fields up to 6 T. The superconducting energy gap Δ of the system is found to be scattered between 1 and 1.2 meV which gives the 2Δ/k T_c ratio between BCS weak-coupling value of ~3.5 and a strong coupling of about 4.2. The excess current evaluated in magnetic field indicates the presence of a single energy gap.

7

The Superconducting Transition in Boron Doped Silicon Films

68%

Kociniewski T., Débarre D., Grockowiak A., Kačmarčík J., Marcenat C., Bustarret E., Ortega L., Klein T., Prudon G., Dubois C., Gautier B., Dupuy J.

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issue 5

1026-1027

EN

We report on a detailed analysis of the superconducting properties of boron-doped silicon films grown along the 001 direction by gas immersion laser doping. This technique is proved to be a powerful technique to dope silicon in the alloying range 2-10 at.% where superconductivity occurs. The superconducting transitions are sharp and well defined both in resistivity and magnetic susceptibility. The variation of T_{c} on the boron concentration is in contradiction with a classical exponential dependence on superconducting parameters. Electrical measurements were performed in magnetic field on the sample with c_{B} = 8 at.% (400 laser shots) which has the highest T_{c} (0.6 K). No hysteresis was found for the transitions in magnetic field, which is characteristic of a type-II superconductor. The corresponding upper critical field was on the order of 1000 G at low temperatures, much smaller than the value previously reported. The temperature dependence of H_{c2} is very well reproduced by the linearized Gorkov equations neglecting spin effects in the very dirty limit. These measurements in magnetic field allow an estimation of the electronic mean-free path, the coherence length, and the London penetration depth within a simple two-band free electron model.

Refine search results

Specific Heat Study of Superconductivity in Cu_{0.061}TiSe_{2}

Phase Diagram of TmB_4 Probed by AC Calorimetry

Two-Gap Superconductivity in 2H-NbS_2

Local Magnetometry of Cu_{0.064}TiSe_{2}

AC Microcalorimetry of Superconducting MgCNi_3 Single Crystals

Point-Contact Spectroscopy of Superconducting MgCNi_3 Single Crystals

The Superconducting Transition in Boron Doped Silicon Films