Flexible magnetoelectric sensor and nonvolatile memory based on magnetization-graded Ni/FSMA/PMN-PT multiferroic heterostructure

Abstract

Flexible multiferroic heterostructures are promising to unveil technological developments in wearable magnetic field sensing, nonvolatile memory, soft robotics, and portable energy harvesters. Here, we report an enhanced and a zero-biased magnetoelectric (ME) effect in flexible, cost-effective, and room temperature sensitive Ni/FSMA/PMN-PT magnetization-graded ME heterostructure. Flexible Ni foil with −q (piezomagnetic coefficient) and the ferromagnetic shape memory alloy (FSMA; Ni-Mn-In) layer with +q offers the desired q-grading. The temperature-dependent dielectric behavior shows an anomaly in the martensite transformation regime of the FSMA layer. The Ni/FSMA/PMN-PT ME heterostructure exhibits noteworthy ME output of ∼3.7 V/cm Oe, significantly higher than Ni/PMN-PT (∼1 V/cm Oe). The q-grading-induced bending moment impedes the asymmetry-related flexural strain and strengthens the ME interaction. The zero-bias ME output of ∼0.4 V/cm Oe is ascribed to the interaction between q-grading-induced transverse magnetization and AC magnetic field. Ni/Ni-Mn-In/PMN-PT ME heterostructure displays excellent magnetic field sensing parameters: correlation coefficient, sensitivity, inaccuracy, and hysteresis of 0.99916, ∼0.74 mV/Oe, 1.5% full-scale output (FSO), and 1.8% FSO, respectively. The reversible and repeatable nonvolatile switching of the ME coefficient obtained with positive and negative electric fields is useful for next-generation memory devices. The flexible ME heterostructure shows no degradation in performance up to 1500 bending cycles. Such Ni/FSMA/PMN-PT based ME heterostructures are propitious for multifunctional flexible magnetic field sensors and nonvolatile memory applications.

Multifunctionality in Electrically Poled PMN–PT/Ni–Mn–In Multiferroic Heterostructure for Flexible Magnetic Field Sensing and Nonvolatile Memory Applications

“…Figure a shows the XRD pattern of the PMN–PT/FSMA multiferroic heterostructure fabricated on the flexible SS substrate. The (220) and (311) reflections at ∼42.15° and ∼50.64° represent the cubic L2 1 structure of the austenitic phase of the FSMA layer. , In addition, the dominant (200) and minor (111) peaks at ∼44.60° and ∼37.62° correspond to the pure perovskite tetragonal phase PMN–PT layer. Additionally, (111) peak corresponding to the face-centered cubic structure of 304L SS substrate is observed at ∼43.53° (JCPDS card no.…”

“…The sensitivity is evaluated from the slope of the induced voltage vs H AC curve and is obtained as ∼0.68 and ∼0.72 mV/Oe in unpoled and electrically poled conditions, respectively. The observed sensitivity values are comparable to the earlier reported results. , Additionally, the inaccuracy is calculated using the relation: inaccuracy = max imum 0.25em deviation 0.25em of 0.25em output 0.25em voltage Full 0.25em scale 0.25em output 0.25em false( FSO false) × 100 % and is obtained as 1.36 FSO and 1.34% FSO without poling and in electrically poled conditions, respectively. Furthermore, the hysteretic performance of the device was checked by sweeping H AC in a complete increasing and decreasing cycle (Figure f).…”

“…The multifunctionality in ME devices can be realized with functional magnetic materials. Ferromagnetic shape memory alloy (FSMA, Ni–Mn–In) is a potential ferromagnetic material as it exhibits a giant magnetostrictive effect. ,, FSMA swiftly responds to frequency and undergoes first-order martensitic transformation near room temperature, providing enormous strain due to variations in the unit cell dimensions. FSMA is a promising material in actuation, memory devices, and magnetic field sensing, owing to its ability to regulate device characteristics via stress, magnetic field, and temperature. − The artificial multiferroic heterostructures comprising highly magnetostrictive FSMA and piezoelectric PMN–PT can provide enhanced ME coupling for futuristic MEMS device applications.…”

“…The interfacial coupling amidst the ferroelectric and ferromagnetic components of ME heterostructures results in electrically and magnetically cross-linked devices that are propitious as magnetic field sensors, transducers, and nonvolatile memory. − Several magnetic field sensors based on the Hall effect, giant magnetoresistance (GMR), tunnel magnetoresistance (TMR), and superconducting quantum interference devices (SQUID) have been reported in the literature. ,, Hall sensors can detect magnetic fields in the T-mT range and are cost-effective, but they cannot detect weak magnetic fields in the μT range and also face miniaturization issues. GMR and TMR-based sensors display appreciable sensitivity, operate at −40 to 125 °C, and can measure magnetic fields in mT range or below. , However, they suffer from high power consumption due to the requirement of external biasing.…”

Pseudocapacitive Kinetics in Synergistically Coupled MoS2–Mo2N Nanowires with Enhanced Interfaces toward All-Solid-State Flexible Supercapacitors

“…The as-prepared MoS 2 –Mo 2 N/SSM flexible electrodes are employed directly in assembling an all-solid-state flexible symmetric supercapacitor (FSSC) with PVA-Na 2 SO 4 hydrogel as the electrolyte. The hydrogel electrolytes, synthesized by infusing a cross-linked polymer matrix with aqueous salt-based electrolyte, facilitate ion conduction and serve as an electrically insulating separator. , Moreover, hydrogel electrolytes offer flexibility, compactness, and electrolyte leakage resistance while providing solid-state characteristics to the assembled FSC device, making them crucial for developing solid-state FSCs. − Prior research on MoS 2 -nanocomposite FSCs generally utilizes chemical synthesis techniques that necessitate extreme temperatures, additional binders, and potentially toxic chemicals/gases. ,,− In this aspect, the present approach of co-sputtering from two separate targets provides a facile, eco-friendly, and readily scalable process for synthesizing nanocomposites without any binders. − Besides, carefully optimizing the sputtering conditions facilitates the homogeneous deposition of seamlessly integrated MoS 2 –Mo 2 N nanocomposite featuring enhanced porosity and better substrate adhesion. ,− Benefiting from the numerous interconnected interfaces and junctions across the MoS 2 –Mo 2 N nanocomposite, the FSSC device exhibits advanced pseudocapacitive kinetics, delivering elevated capacitances, rate capability, higher energy and power densities, ultrastable cyclability, and superb mechanical flexibility. Moreover, the synergistic effect between the seamlessly integrated highly porous MoS 2 nanosheets and highly conducting Mo 2 N nanostructures contributes to the device’s superior performance.…”