You can buy it and both IC cards covered most public transportations, except taxi in Tokyo and around.
Yokohama is one of Tokyo around, same card validity area, no worry.
Suica saler is JR-EAST(biggest rail company in Japan east),
PASMO salers are non-JR rail and bus companies group,
pls read both official web and online guide books.https://www.jreast.co.jp/e/pass/suica.htmlhttps://www.pasmo.co.jp/en/
And Yokohama stn is not only one rail company, be careful.https://en.wikipedia.org/wiki/Yokohama_Stationhttp://www.yokohamajapan.com/information/travel-to-yokohama/
Basically so, using one IC card can not allowed over the card border stn,
it means validity area is own card area only, and have to buy old style paper ticket(s).
Only some exceptions, such as SmartEX service for Tokaido Shinkansen,
but temporary travelers do not use these usual.
However, both cards also works in other regions major card area.
(official web and guide book mentioned)
In other region card area, you can re-charge
at most rail stns, bus payment machine and major covenience stores.
yet you can not card return(refund) and re-issue when broken or lost.
Both and other simlar functions IC cards do not make fare big discounted,
just easiest way to payment and safest if without wallet as own customarily.https://youtu.be/9TuVRCXynpAhttps://youtu.be/s-NyccWXlt4https://youtu.be/rvqitrtmziY
(2nd video guy did some wrong tho but mostly useful, just not perfect and worthful)
So if can not find a best discounted ticket, should post again here ASAP.