Superconductivity in CeBeH<sub>8</sub> and CeBH<sub>8</sub> at moderate pressures
Yu Hou, Bin Li, Yan Bai, Xiaofeng Hao, Yeqian Yang, Fengfeng Chi, Shengli Liu, Jie Cheng, Zhixiang Shi
Abstract
Abstract High-pressure structural searches of superhydrides CeBeH 8 and CeBH 8 were performed under ambient pressure up to 300 GPa. We identify <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>F</mml:mi> <mml:mi>m</mml:mi> <mml:mover> <mml:mn>3</mml:mn> <mml:mo accent="false">‾</mml:mo> </mml:mover> <mml:mi>m</mml:mi> </mml:math> -CeBeH 8 with a superconducting transition temperature T c of 56 K at 10 GPa. Two more phases with spacegroup <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>R</mml:mi> <mml:mover> <mml:mn>3</mml:mn> <mml:mo accent="false">‾</mml:mo> </mml:mover> <mml:mi>m</mml:mi> </mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>C</mml:mi> <mml:mn>2</mml:mn> <mml:mrow> <mml:mo>/</mml:mo> </mml:mrow> <mml:mi>m</mml:mi> </mml:math> , were investigated within the increasing pressures. CeBH 8 shows a similar phase transition process as CeBeH 8 but with higher transition pressures and higher T c . <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>F</mml:mi> <mml:mi>m</mml:mi> <mml:mover> <mml:mn>3</mml:mn> <mml:mo accent="false">‾</mml:mo> </mml:mover> <mml:mi>m</mml:mi> </mml:math> -CeBH 8 is predicted to be superconducting above 120 GPa with a maximum T c of 118 K at 150 GPa. <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>R</mml:mi> <mml:mover> <mml:mn>3</mml:mn> <mml:mo accent="false">‾</mml:mo> </mml:mover> <mml:mi>m</mml:mi> </mml:math> -CeBH 8 and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>C</mml:mi> <mml:mn>2</mml:mn> <mml:mrow> <mml:mo>/</mml:mo> </mml:mrow> <mml:mi>m</mml:mi> </mml:math> -CeBH 8 are dynamically stable above 120 GPa and 100 GPa, respectively. The maximum T c is 123 K at 195 GPa for <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>R</mml:mi> <mml:mover> <mml:mn>3</mml:mn> <mml:mo accent="false">‾</mml:mo> </mml:mover> <mml:mi>m</mml:mi> </mml:math> -CeBH 8 , and 115 K at 350 GPa for <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>C</mml:mi> <mml:mn>2</mml:mn> <mml:mrow> <mml:mo>/</mml:mo> </mml:mrow> <mml:mi>m</mml:mi> </mml:math> -CeBH 8 . Our work enriches the family of ternary hydrides and may provide a useful guideline for further search for superconducting hydrides at low and moderate pressures.