Berlin 2024 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 4: f-Electron Systems

TT 4.5: Talk

Monday, March 18, 2024, 10:45–11:00, H 3005

Quantum Phase Transitions in Ferromagnetic CeAgSb₂ under Pressure — •Christian de Podesta¹, Oliver Squire¹, Jiasheng Chen¹, David Graf², Stanley Tozer², Patricia Alireza¹, and F. Malte Grosche¹ — ¹Cavendish Laboratory, University of Cambridge, UK — ²National High Magnetic Field Laboratory, Tallahassee, Florida, USA

The Kondo lattice system CeAgSb₂ is ferromagnetic below 10 K. Under pressure, CeAgSb₂ displays a complex phase diagram, incorporating quantum phase transitions of both the ambient pressure ferromagnetism and a high-pressure antiferromagnetic phase. Becuase of this, single crystals of CeAgSb₂ are ideal for studying the ferromagnetic quantum phase transition and the corresponding changes to the Fermi surface under pressure.

Here we present transport measurements of the high-pressure phase diagram up to 70 kbar, down to 100 mK and in high magnetic fields. We discuss these findings in relation to the new magnetic phases and tricritical wing structures which emerge at quantum phase transitions in itinerant ferromagnets. At ambient pressure we resolve the entire Fermi surface from Shubnikov de Haas oscillations and find heavy quasi-particles persisting to high fields and long mean free paths, documenting the high quality of our crystals. We present preliminary results of extending these measurements to higher pressures using the tunnel diode oscillator technique in a diamond anvil cell.