Memories are made of this

Researchers at Oxford University have developed a simple method for reading data from a type of computer memory that uses a magnetic rather than an electrical charge to store information.

This reader circuitry could lead to the development of a silicon chip that can store data when its power supply is turned off, just like a hard drive.

The chips could lead to smaller, cheaper and lighter laptops, by eventually removing the need for both a memory section and hard drive, reducing power usage to prolong the battery life. They may also be used in mobile phones or digital cameras.

The millions of transistors within modern silicon chips work like switches to control the flow of electrical current. Spin transistors use the spin, or magnetic, properties of electrons to control current flow. This spin can be set and will not change, meaning the transistor remains in the same magnetic state when power is turned off, unlike normal circuits that need a continuous power supply. The resulting device is known as Magnetic RAM or MRAM.

However, there are problems with reading data from individual components of MRAM, as shrinking the circuitry to do this means it no longer works. ‘The virtual earth MRAM being investigated at the moment has the problem that if you try to read data from one cell you can get strong currents from other cells interfering,’ said Terry Pollard, project manager at Isis Innovation, the university’s technology transfer arm.

The researchers have solved this with their reader circuitry, which is miniaturised and allows the value of each component of MRAM to be read without interference. Existing types of MRAM use a memory section coupled with a large reader section. However, the ISIS device will not require this, allowing memory density to be increased.