Pressure-Induced Superconductivity In Polycrystalline <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi>La</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:msub><mml:mrow><mml:mi>Ni</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">O</mml:mi></mml:mrow><mml:mrow><mml:mn>7</mml:mn><mml:mo>−</mml:mo><mml:mi>δ</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math>
Gang Wang, Ningning Wang, Xiaoli Shen, Jinlin Hou, L. Ma, L. F. Shi, Zhi Ren, Yuhao Gu, Hanming Ma, Pengtao Yang, Ziyi Liu, Haizhong Guo, Jianping Sun, G. M. Zhang, Stuart Calder, Jiaqiang Yan, Bosen Wang, Yoshiya Uwatoko, Jinguang Cheng
Abstract
We synthesized polycrystalline <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:msub><a:mi>La</a:mi><a:mn>3</a:mn></a:msub><a:msub><a:mi>Ni</a:mi><a:mn>2</a:mn></a:msub><a:msub><a:mi mathvariant="normal">O</a:mi><a:mrow><a:mn>7</a:mn><a:mo>−</a:mo><a:mi>δ</a:mi></a:mrow></a:msub></a:mrow></a:math> (<d:math xmlns:d="http://www.w3.org/1998/Math/MathML" display="inline"><d:mrow><d:mi>δ</d:mi><d:mo>≈</d:mo><d:mn>0.0</d:mn><d:mn>7</d:mn></d:mrow></d:math>) samples by using the sol-gel method without postannealing under high oxygen pressure, and then measured temperature-dependent resistivity under various hydrostatic pressures up to 18 GPa by using the cubic anvil and two-stage multianvil apparatus. We find that the density-wave-like anomaly in resistivity is progressively suppressed with increasing pressure and the resistivity drop corresponding to the onset of superconductivity emerges at pressure as low as <f:math xmlns:f="http://www.w3.org/1998/Math/MathML" display="inline"><f:mrow><f:mo form="prefix">∼</f:mo><f:mn>6</f:mn><f:mtext> </f:mtext><f:mtext> </f:mtext><f:mi>GPa</f:mi></f:mrow></f:math>. Zero resistivity is achieved at 9 GPa below <i:math xmlns:i="http://www.w3.org/1998/Math/MathML" display="inline"><i:mrow><i:msubsup><i:mi>T</i:mi><i:mi mathvariant="normal">c</i:mi><i:mrow><i:mrow><i:mi>zero</i:mi></i:mrow></i:mrow></i:msubsup><i:mo>≈</i:mo><i:mn>6.6</i:mn><i:mtext> </i:mtext><i:mtext> </i:mtext><i:mi mathvariant="normal">K</i:mi></i:mrow></i:math>, which increases quickly with pressure to 41 K at 18 GPa. However, the diamagnetic response was not detected in the ac magnetic susceptibility measurements up to 15 GPa, indicating a filamentary nature of the observed superconductivity in the studied pressure range. The constructed <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" display="inline"><m:mrow><m:mi>T</m:mi><m:mtext>−</m:mtext><m:mi>P</m:mi></m:mrow></m:math> phase diagram reveals an intimate relationship between superconductivity, density-wave-like order, and the strange-metal-like behaviors. The observation of zero-resistance state in the polycrystalline <o:math xmlns:o="http://www.w3.org/1998/Math/MathML" display="inline"><o:mrow><o:msub><o:mi>La</o:mi><o:mn>3</o:mn></o:msub><o:msub><o:mi>Ni</o:mi><o:mn>2</o:mn></o:msub><o:msub><o:mi mathvariant="normal">O</o:mi><o:mrow><o:mn>7</o:mn><o:mo>−</o:mo><o:mi>δ</o:mi></o:mrow></o:msub></o:mrow></o:math> samples under high pressures not only corroborates the recent report of superconductivity in the pressurized <r:math xmlns:r="http://www.w3.org/1998/Math/MathML" display="inline"><r:mrow><r:msub><r:mi>La</r:mi><r:mn>3</r:mn></r:msub><r:msub><r:mi>Ni</r:mi><r:mn>2</r:mn></r:msub><r:msub><r:mi mathvariant="normal">O</r:mi><r:mn>7</r:mn></r:msub></r:mrow></r:math> crystals but also facilitates further studies on this emerging family of nickelate high-<u:math xmlns:u="http://www.w3.org/1998/Math/MathML" display="inline"><u:mrow><u:msub><u:mi>T</u:mi><u:mi mathvariant="normal">c</u:mi></u:msub></u:mrow></u:math> superconductors. Published by the American Physical Society 2024