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PhD student wins prize at Materials and Mechanisms of Superconductivity conference

Sam Cross holds certificate awarded for winning the poster prize. They are stood in front of the poster

Sam Cross holds their prize

16 August 2022

Sam Cross was awarded prize poster at the Vancouver conference

We are very proud to announce that our colleague PhD student Sam Cross has been awarded a prize poster at the Materials and Mechanisms of Superconductivity (M2S) conference (Vancouver, July 17 - 22, 2022). The text below presents the results of their research:

Superconductivity in YH4 Films at Very High Pressures

J. Buhot(1), O. Moulding(1,2), S. Cross(1) , I. Osmond(1), A. Brooks(1), A. McCollam(3), O. Lord(4), S. Friedemann(1)

1 H.H. Wills Physics Laboratory, University of Bristol, Tyndal Avenue, Bristol, BS8 1TL, United Kingdom

2 Institut NEEL CNRS/UGA UPR2940, MCBT, 25 rue des Martyrs BP 166, 38042 Grenoble cedex 9, France

3 High Field Magnet Laboratory (HFML-EMFL) and Institute for Molecules and Materials, Radboud University, Toernooiveld 7, 6525 ED Nijmegen, Netherlands

4 School of Earth Sciences, University of Bristol, Wills Memorial Building, Queen’s Road, Bristol BS8 1RJ, United Kingdom

The discovery of the hydride superconductor H3S in 2015 with a Tc record of 203K at 155GPa has been a cornerstone for the research on hydride at high pressures and the quest for room temperature superconductivity [1]. Since several other superhydride compounds have been synthesized, such as YH6 [2] and YH9 [3, 4], exhibiting superconductivity close to room temperature under megabars pressures. While theoretical works are paving the way to realize new hydrides superconductors, their synthesis within the laboratory remains very challenging. Here we demonstrate a new approach to synthesize YH4 from an elemental yttrium film directly evaporated on the diamond anvil and ammonia borane (NH3BH3) as a hydrogen donor [5]. This method allows a more accurate control of the sample size and helps to reach high hydrogen content in the synthesis. The critical superconducting temperatures observed for YH4 films are consistent with those reported by other independent groups in YH4 bulk [2, 3, 6]. Resistivity measurements up to 34T allow us to extract Hc2(T) and estimate Hc2(T=0) at 40-55T using the Werthamer–Helfand–Hohenberg model [7]. We will also present x-ray diffraction and Raman spectroscopy measurements and discuss the crystal structure of YH4 films.

References

[1]. A. P. Drozdov, et al., Nature 525, 73 (2015).

[2]. I. A. Troyan et al., Advanced Materials 33, 2006832 (2021).

[3]. P. P. Kong et al., Nature Communications 12, 5075 (2021).

[4]. E. Snider et al., Physical Review Letters 126, 117003 (2021).

[5]. Buhot et al., Physical Review B 102, 104508 (2020).

[6]. M. Shao et al., Physical Review B 104, 174509 (2021).

[7]. N. R. Werthamer et al., Physical Review 147, 295 (1966)

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