The 23-year-old Madrid-born forward, who made his full Spain debut against England in February, spent the last 18 months at Deportivo La Coruna, although his registration was held by Atletico Madrid after the capital club exercised a clause in his contract.
Arizmendi, who agreed a six-year deal with Los Che a few weeks ago, will link up with a host of other Spain internationals such as David Villa, Fernando Morientes, David Silva and Ruben Baraja at the Mestalla.
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