ReRAM - Resistive Random Access Memory

Memristors need less energy to work, are faster than modern solid state drives and can save information even when the power is turned off. Memristor (abbreviated from the English 'memory resistor' - "memory resistor") was proposed as the fourth main element of the electrical circuit by Professor of the University of California (Berkeley) Leon Chua in 1971. and was first implemented in practice by the developers of the HP Laboratories, the main research division of the company, in 2006.

In early 2010, HP Labs researchers reported a discovery that memristors could also perform logical operations. This allows us to believe that devices based on memristors can change the existing data processing paradigm using a separate central processor, allowing in the future to perform similar operations directly on chips that store information.

2024

Nickel ferrite will help build chips for non-volatile devices

Scientists from the Moscow Institute of Physics and Technology, in collaboration with colleagues from the Joint Institute for High Temperatures of the Russian Academy of Sciences, as well as researchers from Taiwan and Indonesia, have discovered that point defects in the crystal lattice of nickel ferrite can change its conductivity. This opens up prospects for the creation of high-speed and non-volatile electronic devices, such as resistive memory chips. MIPT announced this on December 16, 2024.

Nickel ferrite is a complex oxide of iron and nickel, which is dark brown, water-insoluble crystals. The compound is known for its mechanical hardness and chemical stability, has a high resistivity and Curie temperature of more than 500 C, which allows it to withstand high temperatures without changing the phase state and magnetic properties. 

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MIPT

It is a promising material for spintronics and resistive memory chip manufacturing. Spin devices use not only the charge of an electron, but also its spin, which creates a magnetic field. Resistive memory works at the speed of operational, but at the same time saves data when the power is turned off, like an external disk. Resistive memory chips are based on the structure: metal - insulator - metal, - said  Vladimir Stegailov, head of the laboratory of supercomputer methods in condensed matter physics at MIPT.

The study showed that many properties of nickel ferrite depend on the presence of defects in the crystal structure, that is, violations in the periodicity of the location of atoms. Scientists have applied ab initio methods (methods of first-principle calculations of electronic structure, which are based on the apparatus of quantum physics, but do not use empirical parameters and are distinguished by mathematical severity) to analyze the structure of the ideal crystal of nickel ferrite and real, having point defects.

The modeling of the orbital ordering effect and the charge transfer process, as well as the determination of the band gap of nickel ferrite, was carried out in the VASP software package using the theory of the electronic density functional.

The density of quantum states of nickel ferrite with a structure of ideal (red) and having point defects: oxygen and double oxygen vacancies (blue and green, respectively) and nickel antisites (purple). Source: Computational Materials Science

The researchers also studied the movement of polarons in the structure of nickel ferrite. These are quasiparticles from the electron and the polarization field caused by the deformation of the crystal lattice. It was found that the polaronic conductivity depends on the presence of oxygen vacancies in the nickel ferrite structure and antisites of defects manifested when the nickel cation takes the place of iron.

Scientists have found that conduction channels from double oxygen vacancies can form in nickel ferrite crystals, which increases hole conduction and reduces the width of the forbidden zone.

{{quote 'We can expect that complex primary-principle calculations of the electronic structure of nickel ferrite and similar materials will contribute to the development of fast-acting and non-volatile electronic devices, - summed up Vladimir Stegailov. }}

In Russia, created a platform for the production of memory working without electricity

In early March 2024, Russian specialists from the National Center for Physics and Mathematics (NCPM) announced the development of a single technological platform for integrating memristor devices into the domestic process of producing modern silicon chips. Thus, in the Russian Federation, an opportunity has been created to develop the direction of RRAM memory.

RRAM technology involves the creation of resistive random access memory. The essence of the technique is that dielectrics, which in the usual state have a very high resistance, after applying a certain voltage can form low resistance conductive threads inside themselves, and thus turn into a conductor.

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Unsplash

Russian scientists have developed and implemented the topology of an integrated circuit for the production of engergonvolatile RRAM memory based on a combination of traditional silicon technology in terms of control circuits and new information storage technologies developed as part of the scientific program of the NCPM. The new technique makes it possible to use the upper layers of metallization in classic silicon microchips to place memristors in them. This is a passive electrical element capable of changing its resistance depending on the electric charge flowing through it.

According to TASS, referring to the statements of Russian scientists, memristors can be used to create analogues of nerve endings. They can also be used as the basis for very economical, but at the same time fast memory, which combines non-volatile flash drives and high RAM speed.

The resistance of the memristor can vary depending on the electric charge passed through it, that is, the memristor "remembers" the amount of charge passed through it and stores this information in the form of its resistance. Such properties of the memristor open up the possibility of creating long-term memory cells and systems for "computing in memory" on its basis, and memristor memory elements can be more compact and faster than elements of modern flash memory, "says Academician of the Russian Academy of Sciences Igor Kalyaev, co-chairman of scientific areas of the NCPM.[1]

See also

• DRAM Memory (Global Market)
• 3D NAND Flash Memory
• NVRAM Non Volatile Random Access Memory
• Ferroelectric RAM, FeRAM, FRAM
• MRAM (magnetoresistive random access memory)

Notes