Spin-carrier coupling induced ferromagnetism and giant resistivity peak in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi mathvariant="normal">EuCd</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi mathvariant="normal">P</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:math>
Veronika Sunko, Yue Sun, Mayia Vranas, C. C. Homes, Changmin Lee, Elizabeth Donoway, Zhicheng Wang, Sudhaman Balguri, Mira B. Mahendru, Alejandro Ruiz, Brandon Gunn, R. Basak, S. Blanco-Canosa, E. Schierle, E. Weschke, Fazel Tafti, A. Frano, J. Orenstein
Abstract
$\mathrm{Eu}{\mathrm{Cd}}_{2}{\mathrm{P}}_{2}$ is notable for its unconventional transport: upon cooling the metallic resistivity changes slope and begins to increase, ultimately 100-fold, before returning to its metallic value. Surprisingly, this giant peak occurs at 18 K, well above the N\'eel temperature (${T}_{N}$) of 11.5 K. Using a suite of sensitive probes of magnetism, including resonant x-ray scattering and magneto-optical polarimetry, we have discovered that ferromagnetic order onsets above ${T}_{N}$ in the temperature range of the resistivity peak. The observation of inverted hysteresis in this regime shows that ferromagnetism is promoted by coupling of localized spins and itinerant carriers. The resulting carrier localization is confirmed by optical conductivity measurements.