When transitions freeze: kinetic hindrance and tunable resistance states in an antiferromagnetic Kondo metal

The coexistence of long-range magnetic order (LRMO) with glassy states has been explored for energy efficient memory applications in antiferromagnetic (AFM) systems [1]. In this context we study CeCoGe₃, a non-centrosymmetric tetragonal (I4mm) heavy-fermion candidate with a rich magnetic field-temperature (H–T) phase diagram [2] and pressure-induced superconductivity [3]. For H = 0, CeCoGe₃ exhibits three successive magnetic transitions at T₁=21 K, T₂=12 K, and T₃=8 K with magnetic propagation vectors k₁=(0,0,2/3), k₂=(0,0,5/8), k₃=(0,0,1/2); moments lie along c, with a ferromagnetic (FM) component above T₃ and totally AFM below [4].

Using thermodynamic and electrical transport measurements, we show the transitions at T₂ and T₃ are first-order. Anisotropic resistivity reveals tetragonal symmetry breaking below T₂, indicating a coupled structural change. Field cooling with H II c kinetically arrests the transitions, where disorder from the structural change stabilizes a magnetic glass consisting of AFM–FM phase coexistence that persists below T₃, where memory effects are observed. The field-cooling value sets the relative AFM/FM phase fraction, yielding tunable resistance states. We discuss CeCoGe₃ as a model of kinetically hindered phase transitions relevant to nonvolatile memory, and as a framework to understand materials where glassy behavior coexists with LRMO.

[1] Sci. Adv. 7, eabd8452 (2021).

[2] PRB 47, 839 (1993).

[3] JMMM 310, 844 (2007).

[4] PRB 88, 134416 (2013).