使用R将数字和字符数据从一列分为两列

I would like to separate the values of the "Code" column into two columns named "Country_Code" and "Product_Code" where the country code will be a character vector(such as AE, BA, UAE) and the product code will be numeric (such as 0303,0306). Right now all the values of the "Code" column are the character.
a <- data.frame(Code= c("AE", "0303","0306","0701","BA","UAE","6120"))