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[YNi2B2C_2025_v4SM.pdf](https://mdr.nims.go.jp/filesets/ef9cc578-a3b5-4d3b-88c3-187283f072ce/download)

## Creator

[Taichi Terashima](https://orcid.org/0000-0001-9239-0621), [Hiroyuki Takeya](https://orcid.org/0000-0001-9445-4705), [Hisatomo Harima](https://orcid.org/0000-0003-1741-4368)

## Rights

© 2026 American Physical Society[In Copyright](http://rightsstatements.org/vocab/InC/1.0/)

## Other metadata

[Fermi-Surface-Sheet Dependent Electron-Phonon Coupling in a Borocarbide Superconductor                    <math display="inline">                      <mrow>                        <msub>                          <mrow>                            <mtext>YNi</mtext>                          </mrow>                          <mrow>                            <mn>2</mn>                          </mrow>                        </msub>                        <msub>                          <mrow>                            <mi>B</mi>                          </mrow>                          <mrow>                            <mn>2</mn>                          </mrow>                        </msub>                        <mi>C</mi>                      </mrow>                    </math>](https://mdr.nims.go.jp/datasets/557cb173-71b5-4341-91ed-872c5fae8ab2)

## Fulltext

ver4SMFermi-surface-sheet dependent electron-phonon coupling in a borocarbidesuperconductor YNi2B2CTaichi Terashima,1, ∗ Hiroyuki Takeya,2 and Hisatomo Harima31Research Center for Materials Nanoarchitectonics (MANA),National Institute for Materials Science, Tsukuba 305-0003, Japan2Research Center for Energy and Environmental Materials (GREEN),National Institute for Materials Science, Tsukuba 305-0047, Japan3Department of Physics, Kobe University, Kobe 657-8501, Japan(Dated: June 23, 2026)CRYSTAL GROWTH AND CHARACTERIZATIONSingle crystals of YNi2B2C were grown by a floating zone method without a crucible to avoid impurity inclusionsinto grown crystals, as detailed in [SM1]. The crystals were examined by SEM, EPMA and X-ray diffraction techniqueand found to be of high quality without any secondary phase. Details of the results of these characterizations canbe found in Refs. [SM1–SM3] (the dHvA measurements reported in the present paper were performed between 1995and 1997, in parallel with these characterizations). The lattice parameters were a = 3.5265(1) and c = 10.5415(3) Å,which are in excellent agreement with those reported in [SM4]. The superconducting transition was observed at Tc =15.6 K (onset) with a very narrow transition width of 0.7 K [SM1]. The residual resistivity ratio RRR was 29.3 withelectrical current applied along the a-axis, and the resistivity at Tc was 2.89 µΩcm.DE HAAS–VAN ALPHEN MEASUREMENTSThe reported dHvA measurements were performed with the field-modulation technique [SM5, SM6], and detectionwas made at the second harmonic of the modulation frequency. The modulation frequency and amplitude were typi-cally 67 Hz and 10 mT, respectively. The insets of Fig. 2 (main text) show examples of raw data without backgroundsubtraction. The effective mass m∗ for each frequency (orbit) was determined by fitting the temperature reductionfactor RT of the Lifshitz-Kosevich formula to the experimental temperature dependence of the oscillation amplitude,which was determined by Fourier transformation: RT = X/ sinhX, where X = rKµ∗T/B for a fundamental (r = 1)or a r-th harmonic frequency, µ∗ = m∗/me, and the coefficient K is 14.69 T/K [SM5]. Figures S1 and S2 showexamples of mass determination.BAND-STRUCTURE CALCULATIONSThe band-structure calculations are carried out by using FLAPW method based on the local density approximation(LDA) formula proposed by Gunnarsson and Lundqvist [SM7]. As mentioned in the main text, we shifted the Y dand Ni d levels upward from the LDA levels by 0.11 and 0.05 Ry, respectively. The method of the calculation andthe parameters used are the same as those in the previous one [SM8], except the number of sampling k-points. Theexperimentally observed lattice constants are used: a = 3.526 Å, c = 10.543 Å, and z(B) = 0.358 [SM4]. Muffin-tin(MT) radii are set as 0.1747a, 0.1358a, 0.1010a, and 0.1010a for Y, Ni, B, and C respectively. Core electrons (Kr-coreminus 4p6 for Y, Ar-core minus 3p6 for Ni, He core for B and C) are calculated inside the MT spheres. 4p6 electronson Y and 3p6 electrons on Ni are calculated as valence electrons by using the second energy window. The scalarrelativistic effects are taken into account for all electrons, and the spin-orbit coupling is considered self-consistentlyfor all valence electrons inside the MT spheres as in a second variational procedure. The LAPW basis functions aretruncated at |k + Gi| = 4.01× 2π/a corresponding to 403 LAPW functions at the Γ point.The sampling 767 k-points (divided by 24, 24, and 8) are uniformly distributed in the irreducible 1/16th of thebct Brillouin zone (BZ), instead of 369 k-points (divided by 16, 16, and 8) in the previous work [SM8]. Accordingly,the energies are calculated at about twice as many points within each kz = constant plane compared to the previousstudy. To draw the perspective view of the Fermi surfaces and calculate the extremal areas, the energy eigenvaluesare interpolated at the 226,981 mesh points.26000500040003000200010000Amplitude (a. u.)300025002000150010005000F (T)B // [001]9.13 - 13.5 T       T = 0.04 K 0.20 K 0.41 K 0.71 K 1.0 K 1.4 K 1.7 Kα2α3α4α640062006000580056001.51.00.50.0T (K)10008006004002000Amplitude (a. u.)α2α3α4α(a) (b)FIG. S 1. Effective mass of α. (a) Fourier transforms of oscillations measured with B ‖ c at indicated temperatures. (b)Temperature dependences of oscillation amplitudes for α, 2α, 3α, and 4α. The solid lines are fits to RT , which yield m∗/me= 0.36(3), 0.33(2), 0.35(1), and 0.33(1), respectively, where the errors in parentheses are numerical fitting errors. From theweighted average, we conclude m∗/me = 0.34(2).120010008006004002000Amplitude (a. u.)121086F (kT)     T =  0.04 K 0.10 K 0.30 K 0.50 K 0.65 K 0.80 K 1.0 K 1.2 KB // [001]12.65 - 13.75 Tβγ14001300120011001000900800700Amplitude (a. u.)1.20.80.40.0T (K)5004003002001000-100Amplitude (a. u.)βγ(a) (b)FIG. S 2. Effective masses of β and γ. (a) Fourier transforms of oscillations measured with B ‖ c at indicated temperatures.(b) Temperature dependences of oscillation amplitudes for β and γ. The solid lines are fits to RT , which yield m∗/me = 1.32(3)and 3.3(1), respectively, where the errors in parentheses are numerical fitting errors.ESTIMATION OF λTable S1 provides the source data for the mass enhancement factor λ shown in Fig. 4.∗ TERASHIMA.Taichi@nims.go.jp[SM1] H. Takeya, T. Hirano, and K. Kadowaki, Single crystal growth of quaternary superconductor YNi2B2C by a floatingzone method, Physica C 256, 220 (1996).[SM2] H. Takeya, K. Kadowaki, K. Hirata, and T. Hirano, Single crystal growth and physical properties of YNi2B2C andHoNi2B2C, J. Alloys Compd. 245, 94 (1996).3kz = 0kz = 0.4(π/c)kz = 0.8(π/c)kz = 0.2(π/c)kz = π/ckz = 0.6(π/c)(a) (b)ZZΓΓband 26(c)φζXΓFIG. S 3. (a) Calculated band structure. (b) Cross-sections of the band-26 Fermi surface. (c) ζ and φ orbits on the band-26Fermi surface.[SM3] H. Takeya, K. Kadowaki, K. Hirata, T. Hirano, and K. Togano, Growth of YNi2B2C single crystals and their super-conducting properties, J. Magn. Magn. Mater. 157-158, 611 (1996).[SM4] C. Godart, L. C. Gupta, R. Nagarajan, S. K. Dhar, H. Noel, M. Potel, C. Mazumdar, Z. Hossain, C. Levy-Clement,G. Schiffmacher, B. D. Padalia, and R. Vijayaraghavan, Structural, superconducting, and magnetic properties ofYNi2B2C and ErNi2B2C, Phys. Rev. B 51, 489 (1995).[SM5] D. Shoenberg, Magnetic Oscillations in Metals (Cambridge University Press, Cambridge, 1984).[SM6] T. Terashima, N. Kurita, M. Kimata, M. Tomita, S. Tsuchiya, M. Imai, A. Sato, K. Kihou, C. H. Lee, H. Kito,H. Eisaki, A. Iyo, T. Saito, H. Fukazawa, Y. Kohori, H. Harima, and S. Uji, Fermi surface in KFe2As2 determined viade Haas-van Alphen oscillation measurements, Phys. Rev. B 87, 224512 (2013).[SM7] O. Gunnarsson and B. I. Lundqvist, Exchange and correlation in atoms, molecules, and solids by the spin-density-functional formalism, Phys. Rev. B 13, 4274 (1976).[SM8] K. Yamauchi, H. Katayama-Yoshida, A. Yanase, and H. Harima, Band structure calculations and Fermi surfaces ofYNi2B2C, Physica C 412-414, 225 (2004).[SM9] L. H. Nguyen, G. Goll, E. Steep, A. G. M. Jansen, P. Wyder, O. Jepsen, M. Heinecke, and K. Winzer, Fermi surfacestudies of the borocarbide superconductor YNi2B2C, J. Low Temp. Phys. 105, 1653 (1996).[SM10] O. Ignatchik, T. Coffey, J. Hagel, M. Jäckel, E. Jobiliong, D. Souptel, G. Behr, and J. Wosnitza, Magnetic quantumoscillations in the normal state of YNi2B2C, J. Magn. Magn. Mater. 290-291, 424 (2005).4TABLE S I. Experimental and calculated dHvA frequencies and masses, and mass enhancements calculated as λ = m∗/mband−1.The errors quoted for the effective masses are numerical fitting errors, from which the errors for λ were derived.Experiment Calculationθ (◦) Branch F (kT) m∗/me F (kT) mband/me λ[110] α 0.79 0.48(2) 0.84 0.38 0.25(5)[001] γ 11.7 3.3(1) 11.9 1.9 0.72(5)[001] β 7.0 1.32(2) 6.4 0.68 0.93(3)[001] α 0.50 0.34(2) 0.50 0.30 0.13(7)[100] φ 4.5 1.27(1) 4.2 0.53 1.38(2)[100] η 1.8 1.86(2) 1.7 1.32 0.41(2)[100] α 0.83 0.53(6) 0.87 0.42 0.3(1)θ(11̄0) = 7◦a η 5.5 3.2 4.8 2.1 0.54ϕ = 36◦b η 2.7(1) 2.1 2.0 0.35(5)ϕ = 36◦b α 0.54(3) 0.84 0.39 0.37(8)a From [SM9]. The field direction is 7◦ from [001] towards [110]. The frequency was read from Fig. 2 of [SM9].b From [SM10]. The field direction is 36◦ from [100] towards [110]. The frequency values were not given in [SM10].