Anisotropic magnetocaloric effect in Fe_3-xGeTe₂

Area of Science:

• Condensed Matter Physics
• Materials Science
• Spintronics

Background:

• Van der Waals (vdW) materials offer unique properties due to their layered structure.
• Few-layer Fe3-xGeTe2 exhibits gate-tunable room-temperature ferromagnetism, making it promising for spintronics.
• Understanding magnetocaloric properties is crucial for magnetic refrigeration and device applications.

Purpose of the Study:

• To comprehensively investigate the anisotropic magnetocaloric properties of few-layer Fe3-xGeTe2.
• To determine the influence of intrinsic magnetocrystalline anisotropy on magnetic order.
• To evaluate the potential of Fe3-xGeTe2 for spintronics and magnetic cooling applications.

Main Methods:

• Fabrication of few-layer Fe3-xGeTe2 devices with gate-tunability.
• Measurement of anisotropic magnetic entropy change (ΔSM) and adiabatic temperature change (ΔTad) using heat capacity.
• Analysis of field-dependent parameters and relative cooling power (RCP) under different magnetic field orientations (H//ab and H//c).

Main Results:

• Observed temperature-dependent intrinsic magnetocrystalline anisotropy favoring long-range magnetic order in thin Fe3-xGeTe2 crystals.
• Anisotropic magnetocaloric effect with ΔSM scaling into a universal curve for H//ab and H//c.
• Peak ΔSM of 1.20 J kg−1 K−1 and ΔTad of 0.66 K at 5 T (H//c); field dependencies n=0.603(6) and m=1.20(1) for ΔSM and RCP, respectively.

Conclusions:

• Fe3-xGeTe2 exhibits significant anisotropic magnetocaloric properties, tunable via gate voltage.
• The material's properties are suitable for developing advanced spintronics devices and magnetic cooling technologies.
• The observed anisotropy and tunable ferromagnetism highlight Fe3-xGeTe2 as a promising vdW material for future electronic applications.