Field-induced metastability of the modulation wave vector in a magnetic soliton lattice

Abstract

We present magnetic-field-induced metastability of the magnetic soliton lattice in a bilayer ruthenate Ca 3 (Ru 1-x Fe x) 2 O 7 (x = 0.05) through single-crystal neutron diffraction study. We show that the incommensurability of the modulation wave vector at zero field strongly depends on the history of magnetic field at low temperature, and that the equilibrium ground state can be achieved by warming above a characteristic temperature T g ~ 37 K. We suggest that such metastability might be associated with the domain wall pinning by the magnetic Fe dopants.

Comprehensive magnetic phase diagrams of the polar metal Ca3(Ru0.95Fe<

“…4(a) and (b), depending on the applied field-orientation. The neutron-diffraction measurements, however, implied that the system either remains the CAFM-b phase from the higher-field state after H//a is removed, or transforms into a different IC state with smaller incommensurability after H//b is removed[57,63]. Our current complete magnetic phase diagrams suggest that such implication is not fully correct.…”

“…Recent neutron diffraction measurements suggest that Ca3(Ru0.95Fe0.05)2O7 retains the same space group (Bb21m) as the parent compound Ca3Ru2O7, from room temperature to the lowest measured temperature [56,57]. The crystal structure is illustrated in Fig.…”

“…Note that the period of the illustrated IC structures is not to scale. The neutron-diffraction determined AFM-IC structure, for example, has a large periodicity of ∼58 unit cells or ∼315 Å along a-axis [56,57]. (c) and (d) DM interaction analysis for the AFM soliton and FM soliton, respectively.…”

“…We next discuss the possible mechanism for observed nonzero magnetic moment in the IC phase at low temperatures. Figure 5(a) illustrates the IC spin structure determined by neutron diffraction measurements under ZFC conditions [56,57]. The spins are parallel to each perovskite bilayer and antiparallel across each bilayer.…”

“…induced spin-flop-like phase transitions are clear for both H//a and H//b. Zhu et al[57,63] reported the first-order incommensurate-to-commensurate (IC-to-C) magnetic transitions for field along both a-and b-axes using neutron-diffraction measurements. These transitions should correspond to the illustrated transitions of IC+AFM-b to CAFM-b or CAFM-a in Figs.…”