Shuxiang Dong

Multiferroic magnetoelectric composites: Historical perspective, status, and future directions

Multiferroic magnetoelectric materials, which simultaneously exhibit ferroelectricity and ferromagnetism, have recently stimulated a sharply increasing number of research activities for their scientific interest and significant technological promise in the novel multifunctional devices. Natural multiferroic single-phase compounds are rare, and their magnetoelectric responses are either relatively weak or occurs at temperatures too low for practical applications. In contrast, multiferroic composites, which incorporate both ferroelectric and ferri-/ferromagnetic phases, typically yield giant magnetoelectric coupling response above room temperature, which makes them ready for technological applications. This review of mostly recent activities begins with a brief summary of the historical perspective of the multiferroic magnetoelectric composites since its appearance in 1972. In such composites the magnetoelectric effect is generated as a product property of a magnetostrictive and a piezoelectric substance. A...

Near-ideal magnetoelectricity in high-permeability magnetostrictive/piezofiber laminates with a (2-1) connectivity

Theoretically, the two-phase laminated configurations should have even much higher magnetoelectric (ME) effects—however, prior experimental studies have failed to find such an enhancement. Here, the authors report the unleashing of the potential of the (2-1) connectivity configuration: a piezofiber (one-dimension connectivity) layer laminated between two high-permeability magnetostrictive FeBSiC alloy ones (two-dimension connectivity) has near-ideal ME coupling. Very high ME effects of up to 22V∕cmOe (4×10−7s∕m) at 1Hz—an order of magnitude higher than the giant ones—have been found.

Enhanced magnetoelectric effects in laminate composites of Terfenol-D/Pb(Zr,Ti)O3 under resonant drive

We have found that laminate composites consisting of longitudinally magnetized magnetostrictive Terfenol-D and longitudinally poled piezoelectric Pb(Zr,Ti)O3 layers have dramatically enhanced magnetoelectric effects when driven near resonance. The maximum induced magnetoelectric voltage at resonance was ∼10 Vp/Oe, which is ∼102 times higher than previous reports at subresonant frequencies.

Detection of pico-Tesla magnetic fields using magneto-electric sensors at room temperature

The measurement of low-frequency (10−2–103Hz) minute magnetic field variations (10−12Tesla) at room temperature in a passive mode of operation would be critically enabling for deployable neurological signal interfacing and magnetic anomaly detection applications. However, there is presently no magnetic field sensor capable of meeting all of these requirements. Here, we present new bimorph and push-pull magneto-electric laminate composites, which incorporate a charge compensation mechanism (or bridge) that dramatically enhances noise rejection, enabling achievement of such requirements.

Ultrahigh magnetic field sensitivity in laminates of TERFENOL-D and Pb(Mg1/3Nb2/3)O3–PbTiO3 crystals

It has been found that laminate composites of longitudinally magnetized magnetostrictive TERFENOL-D and a transversely poled piezoelectric Pb(Mg1/3Nb2/3)O3–PbTiO3 crystal have extremely high magnetic field sensitivity. At room temperature, an output voltage with an exceptionally good linear response to an ac magnetic field Hac was found over the range of 10−11

Longitudinal and transverse magnetoelectric voltage coefficients of magnetostrictive/ piezoelectric laminate composite: experiments

This paper presents a novel, long-type of magnetostrictive and piezoelectric laminate composite design in which the layers are, respectively, magnetized/poled along their length axes, and a theory for modeling its behavior. Using piezoelectric and magnetostrictive constitutive equations, and an equation of motion, a magneto-elasto-electric bieffect equivalent circuit is developed. The circuit is used to predict the longitudinal and transverse magnetoelectric (ME) voltage coefficients of our Terfenol-D/Pb(Zr/sub 1-x/Ti/sub x/)O/sub 3/ laminate design. It is found that the longitudinal ME voltage coefficient is significantly higher (/spl sim/5x) than the transverse one, and that our new laminate design has significantly higher ME voltage coefficients under small applied direct current (DC) magnetic bias fields than designs reported previously by other groups. Experimental values were found to be coincidental with predicted ones.Magnetostrictive Terfenol-D (Tb/sub x/Dy/sub 1-x/Fe/sub 2/) and piezoelectric (Pb(Zr/sub 1-x/Ti/sub x/)O/sub 3/) magnetoelectric (ME) laminate composites have been investigated experimentally for various modes of operation: longitudinal magnetized/longitudinal polarized (L-L mode), transverse magnetized/longitudinal polarized (T-L mode), and transverse magnetized/transverse polarized (T-T mode) ME modes. We report their experimentally determined performance characteristics based on our previously developed equivalent circuits for these various modes. Predicted and experimental results are in agreement that the L-L mode laminates have enhanced ME effects, and that, under low or zero magnetic bias, the L-L mode ME voltage coefficients are up to a factor of 5-20/spl times/ higher than those of the T-L mode or T-T mode laminates. The maximum ME voltage coefficient of the L-L mode laminates is over 86 mV/Oe under a bias of 500 Oe.

Giant magnetoelectric effect in Metglas/polyvinylidene-fluoride laminates

Here, the authors report thin (<100μm) and flexible magnetoelectric (ME) composites consisting of Metglas (high-μ magnetostriction) and polyvinylidene-fluoride (piezopolymer) layers laminated together. Both unimorph and three-layer configurations have been studied. The authors find that these ME laminates (i) require dc magnetic biases as low as 8Oe to (ii) induce giant ME voltage coefficients of 7.2V∕cmOe at low frequencies, and up to 310V∕cmOe under resonant drive.

Push-pull mode magnetostrictive/piezoelectric laminate composite with an enhanced magnetoelectric voltage coefficient

A magnetoelectric (ME) laminate composite consisting of a symmetric longitudinally poled piezoelectric Pb(Mg1∕3Nb2∕3)O3–PbTiO3 crystal and two longitudinally magnetized magnetostrictive Tb1−xDyxFe2 layers has been developed that has a notably superior ME voltage coefficient, relative to previous laminate configurations. The symmetric nature of the longitudinally poled piezoelectric layer allows for operation in a push-pull mode that optimizes elastic coupling between layers. Our small laminate has a giant ME voltage coefficient of ∼1.6V∕Oe at low frequencies, a significant enhancement of this coefficient to ∼20V∕Oe under resonance drive, and an exceptional low-level magnetic field sensitivity of ∼10−12T at f=f0.

A strong magnetoelectric voltage gain effect in magnetostrictive-piezoelectric composite

A magnetoelectric laminate composite consisting of magnetostrictive Terfenol-D (Tb1–xDyxFe2–y) and piezoelectric Pb(Zr,Ti)O3 layers has an extremely high voltage gain effect of ≈300 at its resonant state, offering potential for high-voltage miniature transformer applications.

Small dc magnetic field response of magnetoelectric laminate composites

We have found that small long-type magnetoelectric (ME) laminate composites of magnetostrictive Tb1−xDyxFe2−y and piezoelectric Pb(Zr,Ti)O3 are quite sensitive to small dc magnetic field (Hdc) variations, when driven by a constant ac magnetic field. The sensitivity limit is Hdc<10−3Oe (10−7Tesla) using a constant amplitude low frequencies drive, and Hdc<10−4Oe (10−8Tesla) under resonant drive. In addition, an unusual ME switching effect—a 180° phase shift—was observed, in response to changes in the sign of a small Hdc.