Magnetic Trampoline Resonators Made of (La,Sr)MnO$_3$ Single-Crystal Thin Films

ACS Sens. 10, 4244-4250 (2025) · DOI: 10.1021/acssensors.5c00448

License: CC BY 4.0.

Abstract

Microelectro-mechanical resonators employing a magnetic element have been proposed for magnetic field sensing applications, but the integration of magnetic materials with standard semiconductor compounds is challenging and requires complex fabrication protocols. We present a different approach relying on (La$_{0.7}$,Sr$_{0.3}$)MnO$_3$ (LSMO), an oxide compound that works both as a structural element for the resonator and a functional magnetic layer. Suspended trampolines are realized in a single-step process from LSMO thin films and show a quality factor of up to 60k and f·Q products reaching 10$^{10}$ Hz. Their magnetic properties are probed by a SQUID magnetometer and magnetic force microscopy, showing a saturation magnetization of 240 kA/m at room temperature and in-plane magnetic domains with a coercivity of 2.5 mT. Being entirely made from a magnetic material, these resonators exhibit a larger magnetic interaction volume compared to other solutions, making them ideal candidates as building blocks for high-sensitivity magnetic field sensors.

Figures

19 panels with data across 3 figures. Each panel page shows the plot, its columns and its files; each data.csv begins with a header naming the paper, the panel, the source, the license and the provenance route.

Fig. 1

Illustrative figure, no extractable data. Shown in the paper PDF.

Fig. 2

• panel (a): Simulated resonance frequency of the first mode (kHz) against isotropic in-plane tensile stress (MPa) for trampolines with pit diagonal $d$ = 200, 300, 400, 500, 600 and 700 $\mu$m, one curve each. The inset drawing of the mode shape in the print is not reproduced. data.csv
• panel (b): Resonance frequency of the first mode (kHz) of the measured trampolines against pit diagonal $d$ ($\mu$m), as dots (Data), with three dashed lines of simulated values at tensile stress 200, 300 and 400 MPa. The print labels the 200 and 400 MPa lines beside the curves. data.csv
• panel (c): Isotropic in-plane tensile stress $\sigma$ (MPa) of each measured trampoline against pit diagonal $d$ ($\mu$m), one dot per device. data.csv
• panel (d): Ring-down of the first mode of the trampoline with $d$ = 700 $\mu$m: amplitude normalized to its initial value (V/V, logarithmic axis) against time (s), as dots (Data), with a dashed curve (Fit). The print annotates $\tau$ = 173 ms, $f$ = 105.5 kHz and Q = 57300. data.csv
• panel (e): Q factor divided by $10^3$ of each measured trampoline against pit diagonal $d$ ($\mu$m), one dot per device. data.csv
• panel (f): Product of resonance frequency and Q factor, $f \cdot Q$ (Hz, logarithmic axis), of each measured trampoline against pit diagonal $d$ ($\mu$m), one dot per device. data.csv

Fig. 3

• panel (a): In-plane magnetization measured at 50 mT (kA/m, left axis, green dots) and electrical resistance ($\Omega$, right axis, blue squares) against temperature (K). The dotted vertical line marks 25 $^\circ$C. The inset drawing of the field direction in the print is not reproduced. data.csv
• panel (b): Magnetization loop at 25 $^\circ$C: magnetization (kA/m) against applied field $\mu_0 H$ (mT), points joined by a line in the order measured, shown over $\pm 500$ mT as printed. The box and guide lines of the print, which mark the region magnified in (c), are not reproduced. data.csv
• panel (c): Magnification of the magnetization loop of (b): magnetization (kA/m) against applied field $\mu_0 H$ (mT) over $\pm 6$ mT, points joined by a line in the order measured. data.csv

Fig. 4

• panel (a): Surface topography of a clamped rectangular trampoline: height (nm) over a 50 by 50 $\mu$m scan, on the 0 to 300 nm colour scale of the print. The 10 $\mu$m scale bar and the lattice direction arrows of the print are not reproduced; the hosted axes give position in $\mu$m. data.csv
• panel (b): Magnetic force microscopy phase (deg) over the 50 by 50 $\mu$m region of (a), without premagnetization. The print gives no axis or colour scale; the hosted axes give position in $\mu$m and the colour bar the phase. The dashed box of the print, which marks the magnified region, is not reproduced. data.csv
• panel (b-inset): Magnified region of panel (b): magnetic force microscopy phase (deg) over a 10 by 10 $\mu$m scan, without premagnetization. The print gives no axis or colour scale; the hosted axes give position in $\mu$m and the colour bar the phase. data.csv
• panel (c): Magnetic force microscopy phase (deg) over the 50 by 50 $\mu$m region of (a) after applying 20 mT in-plane. The print gives no axis or colour scale; the hosted axes give position in $\mu$m and the colour bar the phase. The dashed box of the print, which marks the magnified region, is not reproduced. data.csv
• panel (c-inset-1): Magnified region 1 of 6 of panel (c), labelled 0 mT in the print: magnetic force microscopy phase (deg) over a 25 by 12.5 $\mu$m scan of the clamped edge, with a magnetic field applied in the reverse direction. The print gives no axis or colour scale; the hosted axes give position in $\mu$m and the colour bar the phase. data.csv
• panel (c-inset-2): Magnified region 2 of 6 of panel (c), labelled 0.5 mT in the print: magnetic force microscopy phase (deg) over a 25 by 12.5 $\mu$m scan of the clamped edge, with a magnetic field applied in the reverse direction. The print gives no axis or colour scale; the hosted axes give position in $\mu$m and the colour bar the phase. data.csv
• panel (c-inset-3): Magnified region 3 of 6 of panel (c), labelled 1 mT in the print: magnetic force microscopy phase (deg) over a 25 by 12.5 $\mu$m scan of the clamped edge, with a magnetic field applied in the reverse direction. The print gives no axis or colour scale; the hosted axes give position in $\mu$m and the colour bar the phase. data.csv
• panel (c-inset-4): Magnified region 4 of 6 of panel (c), labelled 2 mT in the print: magnetic force microscopy phase (deg) over a 25 by 12.5 $\mu$m scan of the clamped edge, with a magnetic field applied in the reverse direction. The print gives no axis or colour scale; the hosted axes give position in $\mu$m and the colour bar the phase. data.csv
• panel (c-inset-5): Magnified region 5 of 6 of panel (c), labelled 3 mT in the print: magnetic force microscopy phase (deg) over a 25 by 12.5 $\mu$m scan of the clamped edge, with a magnetic field applied in the reverse direction. The print gives no axis or colour scale; the hosted axes give position in $\mu$m and the colour bar the phase. data.csv
• panel (c-inset-6): Magnified region 6 of 6 of panel (c), labelled 4 mT in the print: magnetic force microscopy phase (deg) over a 25 by 12.5 $\mu$m scan of the clamped edge, with a magnetic field applied in the reverse direction. The print gives no axis or colour scale; the hosted axes give position in $\mu$m and the colour bar the phase. data.csv

Cite

Nicola Manca, Dhavalkumar Mungpara, Leonélio Cichetto, Alejandro Enrique Plaza, Gianrico Lamura, Alexander Schwarz, Daniele Marré, Luca Pellegrino. Magnetic Trampoline Resonators Made of (La,Sr)MnO$_3$ Single-Crystal Thin Films. ACS Sens. 10, 4244-4250 (2025). https://doi.org/10.1021/acssensors.5c00448

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