EPR linewidth studies of Gd³⁺‐doped LaxCe1−xF₃ single crystals

EPR linewidths of Gd 3+ ions (0.1%) in La x Ce 1− x F 3 single crystals at the frequency 9.4 GHz and temperatures of 77 to 297 K are investigated for H ∥ z . The generalized theory of the magnetic resonance by Kubo and Tomita and Mitsuma's mechanism of spin‐lattice modulated narrowing are adapted to explain the temperature dependence of the EPR linewidths of the Gd 3+ ions at the Kramers host Ce 3+ ions (4f 1 , 2 F 5/2 ) in La x Ce 1− x F 3 single crystals for x ⩽ 0.2. The spin‐lattice narrowing is not observed for x > 0.2. EPR linewidth of Gd 3+ does not depend on the temperature for x > 0.2. Peak‐to‐peak linewidth Δ H pp increases with the decreasing amount of diamagnetic lanthanum ions in La x Ce 1− x F 3 single crystals for 0.6 ⩽ x ⩽ 1.