Observation of Linear Resistance at Low Temperatures in Hole-Doped Degenerate Spin-Valley Semiconductors

Linear resistivity-temperature (<i>R</i>-<i>T</i>) at low temperatures, referred to as strange metal (SM), is an unusual characteristic observed in strongly correlated systems. SM is often mingled with superconductivity and magnetism in various materials. Here, we report a linear <i>R</i>-<i>T</i> relation in a hole-doped, degenerate spin-valley (SV) semiconductor, V_0.25W_0.75Se₂, with hole pockets in the valence band. SM emerges over a wide temperature range (1.8-150 K) without any apparent superconductivity down to 110 mK. This SM behavior is suppressed at low temperatures below 20 K in the presence of a magnetic field. The ansatz <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>R</mml:mi><mml:mrow><mml:mo>(</mml:mo><mml:mi>H</mml:mi><mml:mo>,</mml:mo><mml:mi>T</mml:mi><mml:mo>)</mml:mo></mml:mrow><mml:mo>-</mml:mo><mml:mi>R</mml:mi><mml:mrow><mml:mo>(</mml:mo><mml:mn>0</mml:mn><mml:mo>,</mml:mo><mml:mn>0</mml:mn><mml:mo>)</mml:mo></mml:mrow><mml:mo>∝</mml:mo><mml:msqrt><mml:mrow><mml:msup><mml:mrow><mml:mrow><mml:mo>(</mml:mo><mml:mi>α</mml:mi><mml:msub><mml:mrow><mml:mi>k</mml:mi></mml:mrow><mml:mrow><mml:mi>B</mml:mi></mml:mrow></mml:msub><mml:mi>T</mml:mi><mml:mo>)</mml:mo></mml:mrow></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msup><mml:mo>+</mml:mo><mml:msup><mml:mrow><mml:mrow><mml:mo>(</mml:mo><mml:mi>γ</mml:mi><mml:msub><mml:mrow><mml:mi>μ</mml:mi></mml:mrow><mml:mrow><mml:mi>B</mml:mi></mml:mrow></mml:msub><mml:msub><mml:mrow><mml:mi>μ</mml:mi></mml:mrow><mml:mrow><mml:mn>0</mml:mn></mml:mrow></mml:msub><mml:mi>H</mml:mi><mml:mo>)</mml:mo></mml:mrow></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:msqrt></mml:math> yields the γ/α ratio of ∼4, larger than the previous reports. The observed SM over a wide temperature range is explained by a spin-orbit coupling (SOC)-mediated SV pair with strong correlation effects, analogous to a phonon-mediated Cooper pair in superconductivity. This finding opens possible routes for understanding strange metal behavior through the interplay of strong SOC and strong Coulomb interactions.