Specifying the memo field is invalid .
After broadcast the TX, and query hash, you'll find the flag of "memo" remain empty.

{
"base_tx": {
"name": "v0",
"password": "1234567890",
"chain_id": "irishub-stage",
"account_number": "0",
"sequence": "3953",
"gas": "50000",
"fee": "0.4iris",
"gas_adjustment": "1.2"
},
"sender": "iaa1rulhmls7g9cjh239vnkjnw870t5urrutsfwvmc",
"amount": "1iris",
"memo": "abcdefdfaf"
}