Digital electronics
The ability to read, write, and destroy a binary data state is the core of digital computation. In today’s integrated circuits, transistors, a type of semiconductor device, may switch an electrical signal, acting as a bit that can either represent zero or one.

As a result, a transistor is frequently referred to as a simple logic gate or digital device. It functions essentially as a memory cell. The ability to miniaturize transistors and pack ever-increasing numbers of them onto a silicon wafer later spurred the development in power and computing capacity.

Since Moore’s law is under jeopardy and is rapidly nearing a crucial barrier, researchers are frantically searching for alternatives. Using the quantum states of matter to carry out binary computations is one approach.

Another approach is to get the spin state of an atom or electron. Spintronics is a form of computing that enables read/write operations to be performed in states other than the charge state.

Spintronic devices could have an impact on advancements in quantum computing, neuromorphic computing, and high-power data storage. These devices outperform conventional ones in terms of data processing speed and transistor density.

Electron spin

The intrinsic angular momentum of an electron is revealed by its spin, a quantum quantity. Although there is no equivalent quantity in classical physics, the comparison serves to remind us of the particle’s rotation around its own axis.

There are just two possible values for this number: +1/2 and -1/2, where the signs denote the two possible directions—either “up,” or upwards, or “down,” or downwards. As a result, electrons can be compared to small magnets that orbit the elemental nuclei in a manner similar to how the Earth orbits the Sun. With regard to the nucleus, each electron has a distinct spin orientation that can be aligned in either direction.
In the same way that binary code only uses bits 0 and 1, spin only accepts these two values, making it an ideal option for information encoding. As a result, the idea of spintronics—a cutting-edge kind of electronics—was created.

The electron’s spin state has two values, up and down, which are comparable to “0” and “1” in binary data. These values enable the transmission of digital information at a rate faster than that made feasible by silicon technology employed in modern transistors and with ever-decreasing physical dimensions.

It has been challenging to date to find a spintronics-based material that satisfies the two conditions of being able to regulate the direction of the electron’s spin and having a “lifetime” spin, or a life cycle, long enough to allow information to pass through.

Antiferromagnetic materials

A special class of materials (antiferromagnets) with a weak or negligible external interacting magnetic field is essential for the technological realization of spintronics-based systems and is necessary for the shrinking of memory devices. Antiferromagnets mostly possess the following qualities:

• Due to the absence of external magnetization, insensitivity to external fields
• There is no contact with nearby particles
• Minimal switching times (antiferromagnetic resonance is of the order of THz instead of GHz as in ferromagnets)
• Various antiferromagnetic materials, including semiconductors and superconductors

The semimetal Mn3Sn is one fascinating substance. The fact that Mn3Sn exhibits a mild external magnetic field despite not being a perfect antiferromagnet has increased interest in it. The research team was interested in determining whether the Hall effect was caused by this weak magnetic field. A crystal having an anomalous Hall effect in an antiferromagnetic material is basically magnetization-free.

Hall effect

In the Hall effect, the charged particle floats transversely in the direction of electrical conduction and perpendicular to an external magnetic field. The anomalous Hall effect exhibits a similar pattern of activity, but there is no external magnetic field because the magnetic field is created by the lattice structure of the conducting material.

Researchers can explore the properties of antiferromagnets, such as piezomagnetism, which spontaneously mixes mechanical deformation with magnetic moment induction, using the anomalous Hall effect.

Piezomagnetism is a phenomena that occurs in some antiferromagnetic and ferrimagnetic crystals and is distinguished by a linear relationship between the mechanical strain and magnetic polarization of the system. A spontaneous magnetic moment can be produced by applying physical strain to a piezomagnetic material, and physical deformation can be produced by applying a magnetic field.

As a result, unlike magnetostriction, it enables the bidirectional management of a magnetic moment. If it expands in size at room temperature, this phenomenon, like its electric cousin piezoelectricity, might be technologically advantageous.

The piezomagnetic effect has mostly been studied in antiferromagnetic insulators at cryogenic temperatures, according to the authors’ work “Piezomagnetic Switching of the Anomalous Hall Effect in an Antiferromagnet at Room Temperature” published in Nature Physics. Piezomagnetism in Mn3Sn at standard temperatures was recently discovered by the study’s scientific team.

They discovered that the Mn3Sn allows them to regulate both the sign and size of the anomalous Hall effect by applying a modest amount of uniaxial strain, on the order of 0.1%.

Experiment

Testing on a Weyl antiferromagnet by the researchers showed that adding stress raised the outside residual magnetic field.

If the magnetic field were what was causing the Hall effect, the voltage across the material would change. The study showed that the voltage did not vary considerably in actual use. Instead, they came to the conclusion that the orientation of the material’s spinning electrons is what causes the Hall effect.

A weak external magnetic field is maintained by Mn3Sn. According to the researchers’ findings, the arrangement of the spin electrons within the material is what creates the anomalous Hall effect because they were unable to show any corresponding impact on the voltage across the material.

This allows piezomagnetism to be used to regulate the anomalous Hall effect in Mn3Sn in a way that is different from magnetization by uniaxial deformation. The antiferromagnetic crystal may be given a small amount of uniaxial deformation to fine-tune the anomalous Hall effect (conventionally, functional control of the anomalous Hall effect is achieved by applying an external magnetic field).

The experiment, according to the researchers, demonstrates that the Hall effect is a result of quantum interactions between conduction electrons and their spins. Understanding and creating magnetic memory technology require these results to be fully realized.
The experiment demonstrates how the anomalous Hall effect can be controlled by strain-induced lattice changes and the resulting anisotropy of electrons in some materials.

Numerous spintronic memory systems are already in use. MRAM (magnetoresistive random access memory) has been commercialized and may replace electronic memory despite relying on ferromagnetic switching. We are able to make the antiferromagnetic material Mn3Sn work as a basic memory device in the experiment using the same method as ferromagnets in MRAM, proving the material’s ability to transition spin states.