Na Hyun Jo

Use of frit-disc crucibles for routine and exploratory solution growth of single crystalline samples

Solution growth of single crystals from high temperature solutions often involves the separation of residual solution from the grown crystals. For many growths of intermetallic compounds, this separation has historically been achieved with the use of plugs of silica wool. Whereas this is generally efficient in a mechanical sense, it leads to a significant contamination of the decanted liquid with silica fibres. In this paper, we present a simple design for frit-disc alumina crucible sets that has made their use in the growth single crystals from high temperature solutions both simple and affordable. An alumina frit-disc allows for the clean separation of the residual liquid from the solid phase. This allows for the reuse of the decanted liquid, either for further growth of the same phase, or for subsequent growth of other, related phases. In this paper, we provide examples of the growth of isotopically substituted TbCd and icosahedral i-RCd quasicrystals, as well as the separation of (i) the closely related and phases and (ii) and .

Three-dimensionality of the Bulk Electronic Structure in WTe2

We use temperature- and field-dependent resistivity measurements [Shubnikov--de Haas (SdH) quantum oscillations] and ultrahigh resolution, tunable, vacuum ultraviolet (VUV) laser-based angle-resolved photoemission spectroscopy (ARPES) to study the three-dimensionality (3D) of the bulk electronic structure in WTe2, a type-II Weyl semimetal. The bulk Fermi surface (FS) consists of two pairs of electron pockets and two pairs of hole pockets along the X-Gamma-X direction as detected by using an incident photon energy of 6.7 eV, which is consistent with the previously reported data. However, if using an incident photon energy of 6.36 eV, another pair of tiny electron pockets is detected on both sides of the Gamma point, which is in agreement with the small quantum oscillation frequency peak observed in the magnetoresistance. Therefore, the bulk, 3D FS consists of three pairs of electron pockets and two pairs of hole pockets in total. With the ability of fine tuning the incident photon energy, we demonstrate the strong three-dimensionality of the bulk electronic structure in WTe2. The combination of resistivity and ARPES measurements reveal the complete, and consistent, picture of the bulk electronic structure of this material.

Phonon-induced topological transition to a type-II Weyl semimetal

Given the importance of crystal symmetry for the emergence of topological quantum states, we have studied, as exemplified in NbNiTe2, the interplay of crystal symmetry, atomic displacements (lattice vibration), band degeneracy, and band topology. For NbNiTe2 structure in space group 53 (Pmna) - having an inversion center arising from two glide planes and one mirror plane with a 2-fold rotation and screw axis - a full gap opening exists between two band manifolds near the Fermi energy. Upon atomic displacements by optical phonons, the symmetry lowers to space group 28 (Pma2), eliminating one glide plane along c, the associated rotation and screw axis, and the inversion center. As a result, twenty Weyl points emerge, including four type-II Weyl points in the G-X direction at the boundary between a pair of adjacent electron and hole bands. Thus, optical phonons may offer control of the transition to a Weyl fermion state.

Single crystal growth and magnetic properties of the mixed valent Yb containing Zintl phase, Yb14MgSb11

Large crystals of Yb14MgSb11 were grown through a Sn flux method. Magnetic susceptibility measurements yield an effective magnetic moment of 3.4(1) μB, revealing the presence of both divalent and trivalent Yb in Yb14MgSb11. Previously assumed to only contain Yb2+ as in Yb14MnSb11, the mixed valency demonstrates that Yb14MgSb11 is a Zintl phase.

Pressure induced change in the electronic state of Ta4Pd3Te16

We present measurements of superconducting transition temperature, resistivity, magnetoresistivity and temperature dependence of the upper critical field of Ta

Growth and characterization of BaZnGa

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Nodeless superconductivity in the type-II Dirac semimetal PdTe 2 : London penetration depth and pairing-symmetry analysis

Pd

Reduction of the ordered magnetic moment and its relationship to Kondo coherence in Ce1−xLaxCu2Ge2

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Reduction of the ordered magnetic moment and its relationship to Kondo coherence in

Te

On magnetic structure of CuFe2Ge2: Constrains from the 57Fe Mössbauer spectroscopy

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