Flexible Thinking: Rules of Thumb: A Word to the Wise
Happy’s Tech Talk #29: Bend-to-Install Semi-flex FR-4
Connect the Dots: Five Best Practices for Designing Flex and Rigid-flex PCBs
How the Giant Magnetoelectric Effect Occurs in Bismuth Ferrite
May 23, 2016 | MIPTEstimated reading time: 3 minutes
A team of scientists from the Moscow Institute of Physics and Technology (MIPT), the National Research University of Electronic Technology (MIET), and the Prokhorov General Physics Institute have proposed a theoretical model that explains the unexpectedly high values of the linear magnetoelectric effect in BiFeO3 (bismuth ferrite) that have been observed in a number of experiments. The team also suggested a way of further enhancing the effect. The results of the study have been published in the journal Physical Review B.
One particular feature of bismuth ferrite is that in bulk samples, spins of Fe3+ iron ions are arranged in the form of a cycloid. This spin structure can be destroyed by a strong magnetic field or mechanical stress. Without a spin cycloid, bismuth ferrite exhibits a large linear magnetoelectric effect, and this effect was the focal point of the study.
Multiferroics and the magnetoelectric effect
Multiferroics are materials that simultaneously exhibit different ferroic orders, including magnetic, ferroelectric and/or ferroelastic. If there is an interaction between electric and magnetic subsystems in a material, a magnetoelectric (ME) effect may occur.
The magnetoelectric effect is when electric polarization occurs under the influence of an external magnetic field and magnetization occurs under the influence of an electric field. This allows an electric field to be used to control the magnetic properties of a material and a magnetic field to be used to control the electric properties. If the value of the ME effect is high (dozens or hundreds of times higher than normal), it is called a giant ME effect.
The main use of the magnetoelectric effect is in variable and static magnetic field sensors. These sensors are used in navigation systems, electric motors, and also in vehicle ignition systems. Compared to similar devices based on the Hall effect or magnetoresistance, sensors based on the ME effect are more sensitive (according to research, up to one million times more sensitive) and they are also relatively cheap to manufacture.
The ME effect offers exciting possibilities for the use of multiferroics in new types of magnetic memory, e.g. ROM – read only memory. The ME effect could also potentially be used to create high-precision equipment for working with radiation in the microwave range, and to wirelessly transmit power to miniaturized electronic devices.
Bismuth ferrite
The subject of the study was bismuth ferrite (BiFeO3) – a highly promising multiferroic that is very promising in terms of its practical applications. It is planned to be used to create ultra energy-efficient magnetoelectric memory.
In addition, bismuth ferrite exhibits a magnetoelectric effect at room temperature, while in most other magnetoelectrics an ME effect of this magnitude is only observed at extremely low temperatures (below -160 degrees Celsius). Bismuth ferrite is an antiferromagnetic, which means that the magnetic moments of its magnetic sublattices (structures formed by atoms with the same parallel spins) cancel each other out, and the total magnetization of the material is close to zero. However, the spatial arrangement of the spins forms the same cycloidal spin structure (Fig. 1).
In the 1980s it was thought that this multiferroic exhibited only a quadratic magnetoelectric effect (i.e. polarization is quadratically proportional to the applied magnetic field). The fact that the linear magnetoelectric effect “went unnoticed” for a long time had to do with the spin cycloid (Fig. 1): due to the spin cycloid structure, certain characteristics, such as magnetization and the magnetoelectric effect “average out” to zero. However, when bismuth ferrite is placed in a strong magnetic field (greater than a certain critical value), the structure is destroyed and this is accompanied by the emergence of a linear ME effect (when polarization is linearly proportional to the applied field).
Early experiments indicated a low value of the linear magnetoelectric effect in bismuth ferrite (almost one thousand times lower than the actual value), however later experimental studies revealed a large ME effect and it was also demonstrated that by using it in layered structures, record values of the magnetoelectric effect can be achieved.
Share on:
Suggested Items
Beyond Design: High-speed Rules of Thumb
11/21/2024 | Barry Olney -- Column: Beyond DesignThe idiom “rule of thumb” is often used in electronics design and has its origins in the practice of measuring roughly with one’s thumb. Rules of thumb are easy-to-remember, broadly accurate guides or principles based on practice rather than theory. They are used to help feed our intuition to find a quick solution based on experience. We are often forced to use rules of thumb in PCB design in the absence of expensive analysis tools. We also use them to get quick ballpark figures initially and then fine-tune the numbers with further analysis. We can use rules of thumb as a sanity check to assess whether we are using our tools correctly. In this month’s column, I will present some commonly used and helpful rules for high-speed PCB design.
ASMPT: Highly Flexible Die and Flip-chip Bonder for Co-packaged Optics Production
11/20/2024 | ASMPTThe high-precision AMICRA NANO die and flip-chip bonder has been specially developed for the production of co-packaged optics where which optical and electronic components are integrated in a common housing. With its exceptional process stability and a placement accuracy of ±0.2 μm @ 3 σ, this innovative bonding system is ideally equipped for the communication technology of the future.
SEMI Europe Recognizes Schneider Electric as a Leader in Diversity and Inclusion at SEMICON Europa 2024
11/14/2024 | SEMISEMI Europe and the SEMI European Advisory Council for Diversity and Inclusion announced Schneider Electric as the recipient of the 2023 SEMI Industry Leader in Diversity and Inclusion Award. Frederic Godemel, Executive Vice President, Power Systems and Services at Schneider Electric accepted the award presented at SEMICON Europa 2024 during the SEMI Networking Night Dinner.
Foxconn Strengthens Solid-State Battery Investment, Eyes Two-Wheeler Market as Testing Ground
11/12/2024 | TrendForceHon Hai subsidiary Foxconn has recently established Foxconn New Energy Battery (Zhengzhou) Co., Ltd. in Henan, China. The newly formed company will focus on battery manufacturing, sales, and R&D into automotive components.
Exploring Innovation Through Alternate Metals and Sputtering
11/11/2024 | Marcy LaRont, I-Connect007Dr. Evelyne Parmentier has a PhD in physical chemistry from ETH Zurich. She was born in Luxembourg and is now a proud resident of Switzerland, where she has been part of Dyconex’s R&D engineering team for the past two years. Evelyne gave a presentation at the EIPC Summer Conference titled “Functionalization of Printed Circuit Boards Through Introducing Alternate Metals Through Sputtered Layers,” where she asked her audience, “If there are 93 metals in the periodic table, why are we not using more of them?”
Copyright © 2024 I-Connect007 | IPC Publishing Group Inc. All rights reserved.
Log in