The fifth-generation V-NAND memory chips by Samsung use the "Toggle DDR 4.0" interface for the first time in the industry and provide a data transfer speed of up to 1.4 Gbps — an impressive increase of 40 percent over the previous generation. These new 256 Gb chips will soon be followed by 1 Tb offerings.
https://www.notebookcheck.net/Samsung-begins-mass-production-of-fifth-generation-V-NAND-memory.315636.0.html