Observation of a temperature dependent asymmetry in the domain structure of a Pd-doped FeRh epilayer

Abstract

Using x-ray photoelectron emission microscopy we have observed the coexistence of ferromagnetic and antiferromagnetic phases in a (3 at%)Pd-doped FeRh epilayer. By quantitatively analyzing the resultant images we observe that as the epilayer transforms there is a change in magnetic domain symmetry from predominantly twofold at lower temperatures through to an equally weighted combination of both four and twofold symmetries at higher temperature. It is postulated that the lowered symmetry Ising-like nematic phase resides at the near-surface of the epilayer. This behavior is different to that of undoped FeRh suggesting that the variation in symmetry is driven by the competing structural and electronic interactions in the nanoscale FeRh film coupled with the effect of the chemical doping disorder. 7 Current address:

Antiferromagnetic-ferromagnetic phase domain development in nanopatterned FeRh islands

“…It is noted that the final magnetic domains have an elongated shape along the beam direction in this case. This nematic ordering has been seen before in XPEEM experiments on Pd doped FeRh and was attributed to a martensitic transition 11 . In this case without the Pd doping that cannot be the case.…”

Asymmetric “melting” and “freezing” kinetics of the magnetostructural phase transition in B2-ordered FeRh epilayers

“…The coexistence of the two phases has been inferred from transport measurements, 10 previous X-ray diffraction experiments, 22,31,32 X-ray magnetic circular dichroism spectroscopy, 33 and directly imaged using photoemission electron microscopy (PEEM). 17,19,[34][35][36] Here, we show that there is an asymmetry in the nature of the phase transition in FeRh between warming and cooling, determined by high-resolution synchrotron X-ray diffraction that revealed the changes in out-of-plane lattice constant of our epilayers. There is greater separation of the coexisting phases (i.e., distinct spatial regions with a well-defined expanded or contracted lattice constant, corresponding to FM or AF order, respectively) on cooling into the contracted (AF) state than on heating into the expanded (FM) state.…”

“…Snapshots of such a process have been observed by PEEM of the magnetism in FeRh layers. [34][35][36] The peak widths arise from a mix of Scherrer-type broadening and the finite angular resolution of the instrument. The former indicates the vertical spatial extent 39 The latter was determined to be 0:17 and can be deconvoluted from the measured peak width by subtraction in quadrature to yield the appropriate value of cos h for use in the Scherrer formula.…”

Magnetic order multilayering in FeRh thin films by He-Ion irradiation

“…to be highly controllable by substrate strain [4][5][6][7][8], transition metals substitutional doping [4,5,9,10] and mesoscale patterning [11][12][13][14]. Here, we use low-energy He-ion implantation to precisely tune the metamagnetic transition temperature as a function of ion fluence ( Figure 1(a)).…”