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Electric field gradients in MgB$_2$ synthesized at high pressure: $^111$Cd TDPAC study and ab initio calculation

A. V. Tsvyashchenko·L. N. Fomicheva·M. V. Magnitskaya·E. N. Shirani·V. B. Brudanin·D. V. Filossofov·O. I. Kochetov·N. A. Lebedev·A. F. Novgorodov·A. V. Salamatin·N. A. Korolev·A. I. Velichkov·V. V. Timkin·A. P. Menushenkov·A. V. Kuznetsov·V. M. Shabanov·Z. Z. Akselrod
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Abstract

We report the high-pressure synthesis of novel superconductor MgB$_2$ and some related compounds. The superconducting transition temperature of our samples of MgB$_2$ is equal to 36.6 K. The MgB$_2$ lattice parameters determined via X-ray diffraction are in excellent agreement with results of our ab initio calculations. The time-differential perturbed angular correlation (TDPAC) experiments demonstrate a small increase in quadrupole frequency of $^111$Cd probe with decreasing temperature from 293 to 4.2 K. The electric field gradient (EFG) at the B site calculated from first principles is in fair agreement with EFG obtained from $^11$B NMR spectra of MgB$_2$ reported in the literature. It is also very close to EFG found in our $^111$Cd TDPAC measurements, which suggests that the $^111$Cd probe substitutes for boron in the MgB$_2$ lattice.

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A. V. Tsvyashchenko, L. N. Fomicheva, M. V. Magnitskaya, E. N. Shirani, V. B. Brudanin, D. V. Filossofov, O. I. Kochetov, N. A. Lebedev, A. F. Novgorodov, A. V. Salamatin, N. A. Korolev, A. I. Velichkov, V. V. Timkin, A. P. Menushenkov, A. V. Kuznetsov, V. M. Shabanov, Z. Z. Akselrod. 2001-04-28. Electric field gradients in MgB$_2$ synthesized at high pressure: $^111$Cd TDPAC study and ab initio calculation. https://doi.org/10.1016/s0038-1098(01)00229-0

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