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<p>We report on the crystal growth and superconducting properties of the transition-metal dichalcogenide 2H-NbSe<sub>2</sub>. Millimeter-scale 2H-NbSe<sub>2</sub> single crystals with well-defined hexagonal platelets were grown by chemical vapor transport with iodine (I<sub>2</sub>) as the transport agent. Rietveld analysis of X-ray powder diffraction confirms the single-phase P6<sub>3</sub>/mmc space group with <i>a</i> = <i>b</i> = 3.443&#xa0;Å and <i>c</i> = 12.542&#xa0;Å. Electrical transport and magnetic measurements confirm bulk superconductivity (<i>T</i><sub>c</sub> = 7.06&#xa0;K), coexistence of charge density wave order (<i>T</i><sub>CDW</sub> = 33&#xa0;K), and nearly ideal diamagnetism (4<i>πχ</i> ~-0.98 at 2&#xa0;K). Temperature-dependent specific heat shows a clear jump at <i>T</i><sub>c</sub>, which can be analyzed using a two-gap <i>s</i> + <i>s</i>-wave model with different weights. Approximately 97% of the total Sommerfeld coefficient is associated with the larger-gap (<InlineEquation ID="IEq1"> <EquationSource Format="TEX">\(\Delta_{1} \sim 1.68\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi mathvariant="normal">Δ</mi> <mn>1</mn> </msub> <mo>∼</mo> <mn>1.68</mn> </mrow> </math></EquationSource> </InlineEquation>&#xa0;meV), while the smaller-gap (<InlineEquation ID="IEq2"> <EquationSource Format="TEX">\(\Delta_{2} \sim 0.27\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi mathvariant="normal">Δ</mi> <mn>2</mn> </msub> <mo>∼</mo> <mn>0.27</mn> </mrow> </math></EquationSource> </InlineEquation>&#xa0;meV) accounts for the remaining 3%. This work provides useful quantitative information on multiband superconductivity in 2H-NbSe<sub>2</sub> single crystals.</p>

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Specific heat investigation of superconducting properties in 2H-NbSe2 single crystals

  • 期刊论文

  • 发表日期：

    2026年4月10日

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  • Joo Chan Kim,
  • Yeong Uk Choi,
  • Su Min Lee,
  • Jong Yeon Kim,
  • Jung Jin Park,
  • Min Su Yeo,
  • Jong Hun Kim,
  • Jong Hoon Jung

摘要

We report on the crystal growth and superconducting properties of the transition-metal dichalcogenide 2H-NbSe2. Millimeter-scale 2H-NbSe2 single crystals with well-defined hexagonal platelets were grown by chemical vapor transport with iodine (I2) as the transport agent. Rietveld analysis of X-ray powder diffraction confirms the single-phase P63/mmc space group with a = b = 3.443 Å and c = 12.542 Å. Electrical transport and magnetic measurements confirm bulk superconductivity (Tc = 7.06 K), coexistence of charge density wave order (TCDW = 33 K), and nearly ideal diamagnetism (4πχ ~-0.98 at 2 K). Temperature-dependent specific heat shows a clear jump at Tc, which can be analyzed using a two-gap s + s-wave model with different weights. Approximately 97% of the total Sommerfeld coefficient is associated with the larger-gap ( \(\Delta_{1} \sim 1.68\) Δ 1 ∼ 1.68  meV), while the smaller-gap ( \(\Delta_{2} \sim 0.27\) Δ 2 ∼ 0.27  meV) accounts for the remaining 3%. This work provides useful quantitative information on multiband superconductivity in 2H-NbSe2 single crystals.